subject:(Geophysical fluid dynamics)

Cornell University

1. Zhou, Qi. Far-Field Evolution Of Turbulence-Emitted Internal Waves And Reynolds Number Effects On A Localized Stratified Turbulent Flow.

Degree: PhD, Civil and Environmental Engineering, 2015, Cornell University

URL: http://hdl.handle.net/1813/41151

► In this dissertation, internal waves (IWs) and turbulence in the stably stratified ocean are studied via a series of numerical simulations. First of all, internal… (more)

▼ In this dissertation, internal waves (IWs) and turbulence in the stably stratified ocean are studied via a series of numerical simulations. First of all, internal wave beams that are representative of high-mode internal tide originated from the ocean topography and constituent element of turbulence-emitted IWs are studied via direct numerical simulations (DNS), with an emphasis on their reflection at the sea surface as modelled by a free-slip rigid lid. Nonlinear effects due to wave-wave interaction, such as mean flow and harmonics, are investigated; in particular, the amplitude of the wave-driven Eulerian mean flow is found to match the theoretical prediction of an inviscid weakly nonlinear theory. The IW beams can also degrade at late time of reflection due to parametric subharmonic instability. Subsequent particle tracking is performed based the DNS dataset, in an attempt to examine the mass transport driven by the reflecting IW beams. These fully nonlinear computations reveal a horizontal dispersion of ocean tracers with a dispersivity scaling with O(A4 ), where A is the steepness of the IW beam, while small-amplitude analysis accurate to O(A2 ) suggests an exact cancellation of Eulerian mean flow due to wave-wave interaction and the wave-driven Stokes drift. The second topic of the dissertation investigates the manifestation of submerged-turbulence-emitted IWs at the sea surface and the correlation between the IW characteristics to turbulent source of IW. The turbulent wake of a sphere of diameter D towed at speed U is investigated using three-dimensional implicit largeeddy simulations, in a linearly stratified Boussinesq fluid with buoyancy frequency N and kinematic viscosity [nu]. Six simulations are performed at Reynolds numbers Re ≡ U D/[nu] ∈ {5 x 103 , 105 } and Froude numbers Fr ≡ 2U/(N D) ∈ {4, 16, 64}, with the wave-emitting wake located at a fixed distance of 9D below the surface. As the wake evolves for up to O(300) units of buoyancy time scale 1/N , IW characteristics, such as horizontal wavelength [lamda]H and wave period T , are sampled at the sea surface via wavelet transforms of surface horizontal divergence signals. The statistics of amplitudes and orientations of IW-induced surface strains are also reported. The normalized mean observable wavelength [lamda]H /D at the sea surface decays in time as (N t)[-]1 , which is due to the waves' dispersion, the dominant process in the far-field, and is in agreement with a linear propagation model that is independent of the wake Re and Fr. This agreement suggests that, within the Re range considered, the most energetic waves impacting the surface originate from the early-time wake that is adjusting to buoyancy. Questions remain about the efficiency of late-time buoyancy driven stratified turbulence in radiating waves with ˆ considerable energy content. The most energetic wavelength [lamda]H , when normalized by D, is found to scale as Fr 1/3 and decrease with Re, which causes the arrival time (in N t units) of the strongest waves at the surface to scale… Advisors/Committee Members: Diamessis,Peter J. (chair), Pope,Stephen Bailey (committee member), Philpot,William Douglas (committee member).

Subjects/Keywords: Fluid dynamics; Turbulence; Geophysical flows

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhou, Q. (2015). Far-Field Evolution Of Turbulence-Emitted Internal Waves And Reynolds Number Effects On A Localized Stratified Turbulent Flow. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/41151

Chicago Manual of Style (16^th Edition):

Zhou, Qi. “Far-Field Evolution Of Turbulence-Emitted Internal Waves And Reynolds Number Effects On A Localized Stratified Turbulent Flow.” 2015. Doctoral Dissertation, Cornell University. Accessed January 19, 2021. http://hdl.handle.net/1813/41151.

MLA Handbook (7^th Edition):

Zhou, Qi. “Far-Field Evolution Of Turbulence-Emitted Internal Waves And Reynolds Number Effects On A Localized Stratified Turbulent Flow.” 2015. Web. 19 Jan 2021.

Vancouver:

Zhou Q. Far-Field Evolution Of Turbulence-Emitted Internal Waves And Reynolds Number Effects On A Localized Stratified Turbulent Flow. [Internet] [Doctoral dissertation]. Cornell University; 2015. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/1813/41151.

Council of Science Editors:

Zhou Q. Far-Field Evolution Of Turbulence-Emitted Internal Waves And Reynolds Number Effects On A Localized Stratified Turbulent Flow. [Doctoral Dissertation]. Cornell University; 2015. Available from: http://hdl.handle.net/1813/41151

University of Cambridge

2. Parker, Jeremy. Linear and nonlinear dynamics in stratified shear flows.

Degree: PhD, 2020, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/312763

► Stably stratified shear flows, in which a less dense layer of fluid lies above and moves counter to a more dense layer below, are ubiquitous… (more)

▼ Stably stratified shear flows, in which a less dense layer of fluid lies above and moves counter to a more dense layer below, are ubiquitous in geophysical fluid dynamics. These are often found to be unstable if the non-dimensional Richardson number Ri, quantifying the strength of stratification to shear, is sufficiently low. This is of particular importance in oceanography, where shear instabilities are conjectured to be important in the generation of turbulence in the deep ocean, an area of huge uncertainty in contemporary climate models. The Miles-Howard theorem tells us that for a steady, inviscid, parallel shear flow, if the local Richardson number is everywhere greater than one quarter, the flow is stable to infinitesimal perturbations. Though an important result, the strong restrictions in the applicability of this theorem mean care must be used when applying the criterion of Ri > 1/4 for stability. This thesis explores some of these limitations, beginning with an overview in chapter 1. Chapter 2 explores the infinitesimal restriction of the Miles-Howard theorem, by asking whether finite-amplitude perturbations could lead to significant nonlinear behaviour, in a so-called subcritical instability. It is found that while the classical Kelvin-Helmholtz instability does indeed exhibit subcriticality, nonlinear steady states are found only just above Ri = 1/4. Chapter 3 investigates in detail a hitherto unknown linear instability, which was discovered in chapter 2. Behaving similarly to the classic Holmboe instability, it exists for Ri > 1/4 when viscosity is introduced, and reveals new insights into the possible physical interpretations of stratified shear instability. Chapter 4 revisits the results of chapter 2 but considers two cases of the Prandtl number Pr, the ratio of diffusivity of the momentum to density. When Pr = 0.7, as is approximately the case for air, a simple supercritical instability is found. However, for Pr = 7, corresponding approximately to water, strong subcritical behaviour is observed, and it is demonstrated that finite-amplitude perturbations can trigger Kelvin-Helmholtz-like behaviour well above Ri = 1/4. Chapter 5 considers the time-varying, non-parallel flow of an oblique internal gravity wave incident on a shear layer. Using direct-adjoint looping, it is shown that the disturbances which maximise energy after a certain time, so-called linear optimal perturbations, can be convective-like rolls in the spanwise direction, rather than a shear instability, calling into question the relevance of the classical shear instabilities in oceanography. Chapter 6 concludes the thesis with a discussion of the implications of the results.

Subjects/Keywords: Geophysical fluid dynamics; Hydrodynamic stability; Nonlinear dynamics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Parker, J. (2020). Linear and nonlinear dynamics in stratified shear flows. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/312763

Chicago Manual of Style (16^th Edition):

Parker, Jeremy. “Linear and nonlinear dynamics in stratified shear flows.” 2020. Doctoral Dissertation, University of Cambridge. Accessed January 19, 2021. https://www.repository.cam.ac.uk/handle/1810/312763.

MLA Handbook (7^th Edition):

Parker, Jeremy. “Linear and nonlinear dynamics in stratified shear flows.” 2020. Web. 19 Jan 2021.

Vancouver:

Parker J. Linear and nonlinear dynamics in stratified shear flows. [Internet] [Doctoral dissertation]. University of Cambridge; 2020. [cited 2021 Jan 19]. Available from: https://www.repository.cam.ac.uk/handle/1810/312763.

Council of Science Editors:

Parker J. Linear and nonlinear dynamics in stratified shear flows. [Doctoral Dissertation]. University of Cambridge; 2020. Available from: https://www.repository.cam.ac.uk/handle/1810/312763

University of Cambridge

3. Parker, Jeremy. Linear and nonlinear dynamics in stratified shear flows.

Degree: PhD, 2020, University of Cambridge

URL: https://doi.org/10.17863/CAM.59865 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818250

► Stably stratified shear flows, in which a less dense layer of fluid lies above and moves counter to a more dense layer below, are ubiquitous… (more)

▼ Stably stratified shear flows, in which a less dense layer of fluid lies above and moves counter to a more dense layer below, are ubiquitous in geophysical fluid dynamics. These are often found to be unstable if the non-dimensional Richardson number Ri, quantifying the strength of stratification to shear, is sufficiently low. This is of particular importance in oceanography, where shear instabilities are conjectured to be important in the generation of turbulence in the deep ocean, an area of huge uncertainty in contemporary climate models. The Miles-Howard theorem tells us that for a steady, inviscid, parallel shear flow, if the local Richardson number is everywhere greater than one quarter, the flow is stable to infinitesimal perturbations. Though an important result, the strong restrictions in the applicability of this theorem mean care must be used when applying the criterion of Ri > 1/4 for stability. This thesis explores some of these limitations, beginning with an overview in chapter 1. Chapter 2 explores the infinitesimal restriction of the Miles-Howard theorem, by asking whether finite-amplitude perturbations could lead to significant nonlinear behaviour, in a so-called subcritical instability. It is found that while the classical Kelvin-Helmholtz instability does indeed exhibit subcriticality, nonlinear steady states are found only just above Ri = 1/4. Chapter 3 investigates in detail a hitherto unknown linear instability, which was discovered in chapter 2. Behaving similarly to the classic Holmboe instability, it exists for Ri > 1/4 when viscosity is introduced, and reveals new insights into the possible physical interpretations of stratified shear instability. Chapter 4 revisits the results of chapter 2 but considers two cases of the Prandtl number Pr, the ratio of diffusivity of the momentum to density. When Pr = 0.7, as is approximately the case for air, a simple supercritical instability is found. However, for Pr = 7, corresponding approximately to water, strong subcritical behaviour is observed, and it is demonstrated that finite-amplitude perturbations can trigger Kelvin-Helmholtz-like behaviour well above Ri = 1/4. Chapter 5 considers the time-varying, non-parallel flow of an oblique internal gravity wave incident on a shear layer. Using direct-adjoint looping, it is shown that the disturbances which maximise energy after a certain time, so-called linear optimal perturbations, can be convective-like rolls in the spanwise direction, rather than a shear instability, calling into question the relevance of the classical shear instabilities in oceanography. Chapter 6 concludes the thesis with a discussion of the implications of the results.

Subjects/Keywords: Geophysical fluid dynamics; Hydrodynamic stability; Nonlinear dynamics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Parker, J. (2020). Linear and nonlinear dynamics in stratified shear flows. (Doctoral Dissertation). University of Cambridge. Retrieved from https://doi.org/10.17863/CAM.59865 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818250

Chicago Manual of Style (16^th Edition):

Parker, Jeremy. “Linear and nonlinear dynamics in stratified shear flows.” 2020. Doctoral Dissertation, University of Cambridge. Accessed January 19, 2021. https://doi.org/10.17863/CAM.59865 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818250.

MLA Handbook (7^th Edition):

Parker, Jeremy. “Linear and nonlinear dynamics in stratified shear flows.” 2020. Web. 19 Jan 2021.

Vancouver:

Parker J. Linear and nonlinear dynamics in stratified shear flows. [Internet] [Doctoral dissertation]. University of Cambridge; 2020. [cited 2021 Jan 19]. Available from: https://doi.org/10.17863/CAM.59865 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818250.

Council of Science Editors:

Parker J. Linear and nonlinear dynamics in stratified shear flows. [Doctoral Dissertation]. University of Cambridge; 2020. Available from: https://doi.org/10.17863/CAM.59865 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.818250

4. Storer, Benjamin. Development and Application of Models and Diagnostics for Geophysical Fluid Flows.

Degree: 2019, University of Waterloo

URL: http://hdl.handle.net/10012/14320

► This thesis presents the development and application of numerical tools for simulating and diagnosing quasi-geostrophic fluid systems. In this thesis we present a new numerical… (more)

▼ This thesis presents the development and application of numerical tools for simulating and diagnosing quasi-geostrophic fluid systems. In this thesis we present a new numerical model called SPIQG that is pseudo-spectral but also allows for a channel geometry and correctly computes the evolution of the zonal transport while maintaining spectral accuracy. There are numerous numerical models that simulate the non-linear evolution of the continuously stratified Quasi-Geostrophic (QG) system, and many of these models are pseudo-spectral in order to achieve high-order accuracy in the spatial discretization, but those typically assume a doubly-periodic geometry. SPIQG is built using the framework provided by SPINS, a spectral and parallel model for simulating the 3D incompressible, non-hydrostatic, Boussinesq Navier-Stokes equations. This framework provides powerful MPI-based parallelization in order to perform large-scale simulations in high powered computing environments. To validate this model, we present the results from various test cases, including quasi-geostrophic turbulence, jet destabilization, and vortex destabilization. The spectral accuracy allows for the total energy to be very well conserved as well as providing accurate calculation of power spectra, spectral fluxes, and anisotropy metrics. Next, we propose a spectrally computed diagnostic for spatial anisotropy: a measure of the extent to which a field exhibits a bias between different orientations. The diagnostic is presented in the framework of fluid dynamics, but can be applied to any field for which Parseval’s theorem applies and to which discrete Fourier, sine, or cosine transforms can be applied. The proposed metric provides both a local, or per-wavelength, measure of anisotropy, as well as a global measure. In order to determine when the anisotropy of a system is significant, the anisotropy of white noise is diagnosed both analytically and numerically. This reference anisotropy then provides a statistically sound method for determining if the observed field is significantly more or less anisotropic than noise. An idealized geophysical fluid dynamics simulation is used to illustrate the diagnostic power of the proposed metric. These tools are then applied to study the stability of lens-shaped vortices. We compute the stability characteristics with higher accuracy and for a wider range of Burger numbers (Bu) than what was previously done. It is found that there are four distinct Bu-regions of linear instability. Over the primary region of interest, 0.1 < Bu < 10, we confirm that the first and second azimuthal modes are the only linearly unstable modes, and they are associated with vortex tilting and tearing respectively. Moreover, the most unstable first azimuthal mode is not precisely captured by the linear stability analysis because of the extra condition that is imposed at the vortex centre, and accurate calculations of the second azimuthal mode requires higher resolution than was previously considered. We also study the non-linear…

Subjects/Keywords: Fluid dynamics; Computational fluid dynamics; Physical oceanography; Geophysical fluid dynamics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Storer, B. (2019). Development and Application of Models and Diagnostics for Geophysical Fluid Flows. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/14320

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Storer, Benjamin. “Development and Application of Models and Diagnostics for Geophysical Fluid Flows.” 2019. Thesis, University of Waterloo. Accessed January 19, 2021. http://hdl.handle.net/10012/14320.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Storer, Benjamin. “Development and Application of Models and Diagnostics for Geophysical Fluid Flows.” 2019. Web. 19 Jan 2021.

Vancouver:

Storer B. Development and Application of Models and Diagnostics for Geophysical Fluid Flows. [Internet] [Thesis]. University of Waterloo; 2019. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/10012/14320.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Storer B. Development and Application of Models and Diagnostics for Geophysical Fluid Flows. [Thesis]. University of Waterloo; 2019. Available from: http://hdl.handle.net/10012/14320

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

5. Xu, Chengzhu. Numerical Simulations of Internal Solitary and Solitary-Like Waves: Wave Interactions and Instabilities.

Degree: 2019, University of Waterloo

URL: http://hdl.handle.net/10012/14735

► Internal solitary and solitary-like waves (ISWs) are commonly observed in stably stratified fluids such as the Earth's atmosphere and oceans. As these waves interact with… (more)

▼ Internal solitary and solitary-like waves (ISWs) are commonly observed in stably stratified fluids such as the Earth's atmosphere and oceans. As these waves interact with other physical processes and/or move through a varying background environment, they may change their form and possibly become unstable. In this thesis, we study ISWs using high-resolution direct numerical simulations and address three major topics: the interaction of ISWs with short waves, the onset of shear instability in ISWs, and the dynamics of ISWs in a shear background current induced by basin-scale standing internal waves. The first topic examines the behavior of short internal waves as they propagate through large-amplitude ISWs. A key finding is that for waves that are short in comparison to the ISW width, the interaction leads to an almost complete destruction of the short waves, but that longer waves are able to maintain their structure after the interaction. The destruction of short waves occurs primarily due to the velocity shear induced by the ISW, which alters the vertical structure of the short waves so that significant wave activity is found only on the upstream side of the ISW crest (i.e. the deformed pycnocline). These results suggest that through the interaction with waves of relatively smaller length scale, ISWs can provide a means to decrease the power observed in the short-wave band in the coastal ocean. The second topic focuses on the onset and growth of shear instability in ISWs, which is particularly important for the diapycnal mixing in open waters. The complexity of instability onset in ISWs is due to the finite length and the non-parallel structure of the wave-induced high-shear region. We examine large-amplitude ISWs with a flat crest and show that, depending on the ratio of the length of high shear region and the width of the wave, there are cases in which instability can occur spontaneously, cases in which its onset is Reynolds number dependent, and cases in which instability does not occur spontaneously but must be triggered by small, but finite amplitude noise. The amplitude of the noise has a crucial influence on the instability growth, regardless of its spatial structure. In the final topic we study the effect of a shear background current on the dynamics of ISWs by investigating the interaction of ISWs with basin-scale standing internal waves. The ISWs are generated using a lock-release mechanism, while the seiches are created using a tilted tank suddenly returned to the upright position, both of which are readily realizable in a laboratory. In most cases, the wave forms of ISWs in the simulations match those described by the fully nonlinear theory, implying that in laboratory experiments ISWs propagating in a shear background current can be generated in a similar manner. In some circumstances, however, the presence of a shear background current prevents the formation of ISWs, but enables the formation of a finite amplitude dispersive wave train, even when the pycnocline center is not close to the…

Subjects/Keywords: geophysical fluid dynamics; internal waves; numerical simulations

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Xu, C. (2019). Numerical Simulations of Internal Solitary and Solitary-Like Waves: Wave Interactions and Instabilities. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/14735

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Xu, Chengzhu. “Numerical Simulations of Internal Solitary and Solitary-Like Waves: Wave Interactions and Instabilities.” 2019. Thesis, University of Waterloo. Accessed January 19, 2021. http://hdl.handle.net/10012/14735.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Xu, Chengzhu. “Numerical Simulations of Internal Solitary and Solitary-Like Waves: Wave Interactions and Instabilities.” 2019. Web. 19 Jan 2021.

Vancouver:

Xu C. Numerical Simulations of Internal Solitary and Solitary-Like Waves: Wave Interactions and Instabilities. [Internet] [Thesis]. University of Waterloo; 2019. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/10012/14735.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Xu C. Numerical Simulations of Internal Solitary and Solitary-Like Waves: Wave Interactions and Instabilities. [Thesis]. University of Waterloo; 2019. Available from: http://hdl.handle.net/10012/14735

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Oxford

6. MacMackin, Christopher. Understanding the effect of seasonal variability on the structure of ice shelves and meltwater plumes.

Degree: PhD, 2018, University of Oxford

URL: http://ora.ox.ac.uk/objects/uuid:3a546ebe-bd60-42b6-8f98-c1613c344652 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.770679

► Ice shelves are important to the climate system as they control the release of fresh water from ice sheets into the ocean, with consequences for… (more)

Subjects/Keywords: Geophysical Fluid Dynamics; Glaciology; Physics; Mathematical Modelling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

MacMackin, C. (2018). Understanding the effect of seasonal variability on the structure of ice shelves and meltwater plumes. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:3a546ebe-bd60-42b6-8f98-c1613c344652 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.770679

Chicago Manual of Style (16^th Edition):

MacMackin, Christopher. “Understanding the effect of seasonal variability on the structure of ice shelves and meltwater plumes.” 2018. Doctoral Dissertation, University of Oxford. Accessed January 19, 2021. http://ora.ox.ac.uk/objects/uuid:3a546ebe-bd60-42b6-8f98-c1613c344652 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.770679.

MLA Handbook (7^th Edition):

MacMackin, Christopher. “Understanding the effect of seasonal variability on the structure of ice shelves and meltwater plumes.” 2018. Web. 19 Jan 2021.

Vancouver:

MacMackin C. Understanding the effect of seasonal variability on the structure of ice shelves and meltwater plumes. [Internet] [Doctoral dissertation]. University of Oxford; 2018. [cited 2021 Jan 19]. Available from: http://ora.ox.ac.uk/objects/uuid:3a546ebe-bd60-42b6-8f98-c1613c344652 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.770679.

Council of Science Editors:

MacMackin C. Understanding the effect of seasonal variability on the structure of ice shelves and meltwater plumes. [Doctoral Dissertation]. University of Oxford; 2018. Available from: http://ora.ox.ac.uk/objects/uuid:3a546ebe-bd60-42b6-8f98-c1613c344652 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.770679

UCLA

7. Cheng, Jonathan. Characterizing convection in geophysical dynamo systems.

Degree: Geophysics & Space Physics, 2015, UCLA

URL: http://www.escholarship.org/uc/item/69z5f5gz

► The Earth’s magnetic field is produced by a fluid dynamo in the molten iron outer core. This geodynamo is driven by fluid motions induced by… (more)

▼ The Earth’s magnetic field is produced by a fluid dynamo in the molten iron outer core. This geodynamo is driven by fluid motions induced by thermal and chemical convection and strongly influenced by rotational and magnetic field effects. While frequent observations are made of the morphology and time-dependent field behavior, flow dynamics in the core are all but inaccessible to direct measurement. Thus, forward models are essential for exploring the relationship between the geomagnetic field and its underlying fluid physics. The goal of my PhD is to further our understanding of the fluid physics driving the geodynamo.In order to do this, I have performed a suite of nonrotating and rotating convection laboratory experiments and developed a new experimental device that reaches more extreme values of the governing parameters than previously possible. In addition, I conduct a theoretical analysis of well-established results from a suite of dynamo simulations by Christensen and Aubert (2006). These studies are conducted at moderate values of the Ekman number (ratio between viscosity and Coriolis forces, ~ 10^−4), as opposed to the the extremely small Ekman numbers in planetary cores (~ 10^−15). At such moderate Ekman values, flows tend to take the form of large-scale, quasi-laminar axial columns. These columnar structures give the induced magnetic field a dipolar morphology, similar to what is seen on planets. However, I find that some results derived from these simulations are fully dependent on the fluid viscosity, and therefore are unlikely to reflect the fluid physics driving dynamo action in the core. My findings reinforce the need to understand the turbulent processes that arise as the governing parameters approach planetary values. Indeed, my rotating convection experiments show that, as the Ekman number is decreased beyond ranges currently accessible to dynamo simulations, the regime characterized by laminar columns is found to dwindle. We instead find a large variety of behavioral regimes ranging from axial columns to fully three-dimensional turbulence. By comparing these to direct numerical simulations and asymptotically-reduced models, we find broad agreement in both the heat transfer scaling properties and flow morphologies in these separate regimes. In particular, large, multi-scale axial vortices emerge consistently in numerical and asymptotic simulations. Such multi-scale structures in the core may be related to the Earth’s dipolar magnetic field structure. I have designed and fabricated a novel laboratory experimental device capable of characterizing these flow regimes in great detail using accurate heat transfer and velocity measurements and high-resolution flow imaging.

Subjects/Keywords: Geophysics; Core dynamics; Dynamo theory; Geophysical fluid dynamics; Rotating convection

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Cheng, J. (2015). Characterizing convection in geophysical dynamo systems. (Thesis). UCLA. Retrieved from http://www.escholarship.org/uc/item/69z5f5gz

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Cheng, Jonathan. “Characterizing convection in geophysical dynamo systems.” 2015. Thesis, UCLA. Accessed January 19, 2021. http://www.escholarship.org/uc/item/69z5f5gz.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Cheng, Jonathan. “Characterizing convection in geophysical dynamo systems.” 2015. Web. 19 Jan 2021.

Vancouver:

Cheng J. Characterizing convection in geophysical dynamo systems. [Internet] [Thesis]. UCLA; 2015. [cited 2021 Jan 19]. Available from: http://www.escholarship.org/uc/item/69z5f5gz.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Cheng J. Characterizing convection in geophysical dynamo systems. [Thesis]. UCLA; 2015. Available from: http://www.escholarship.org/uc/item/69z5f5gz

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Waterloo

8. Ko, William. High-Resolution Numerical Simulations of Wind-Driven Gyres.

Degree: 2011, University of Waterloo

URL: http://hdl.handle.net/10012/6127

► The dynamics of the world's oceans occur at a vast range of length scales. Although there are theories that aid in understanding the dynamics at… (more)

Subjects/Keywords: Numerical Methods; Geophysical Fluid Dynamics; Quasi-Geostrophic Model; Shallow Water Model

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ko, W. (2011). High-Resolution Numerical Simulations of Wind-Driven Gyres. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/6127

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Ko, William. “High-Resolution Numerical Simulations of Wind-Driven Gyres.” 2011. Thesis, University of Waterloo. Accessed January 19, 2021. http://hdl.handle.net/10012/6127.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Ko, William. “High-Resolution Numerical Simulations of Wind-Driven Gyres.” 2011. Web. 19 Jan 2021.

Vancouver:

Ko W. High-Resolution Numerical Simulations of Wind-Driven Gyres. [Internet] [Thesis]. University of Waterloo; 2011. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/10012/6127.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ko W. High-Resolution Numerical Simulations of Wind-Driven Gyres. [Thesis]. University of Waterloo; 2011. Available from: http://hdl.handle.net/10012/6127

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

9. Khodkar, Mohammad Amin. Vorticity-based modeling of stratified flows.

Degree: 2017, University of California – eScholarship, University of California

URL: http://www.escholarship.org/uc/item/637909vg

► Within the present investigation, the broad span of applications of the vorticity-based modeling concept for stratified flows, based on the simultaneous use of horizontal and… (more)

▼ Within the present investigation, the broad span of applications of the vorticity-based modeling concept for stratified flows, based on the simultaneous use of horizontal and vertical momenta equations in the form of vorticity balance principle, is studied in detail. Towards this objective, this approach, originally introduced by Borden and Meiburg [Z. Borden and E. Meiburg, Phys. Fluids 25 (10), 101301 (2013); Z. Borden and E. Meiburg, J. Fluid Mech. 726, R1 (2013)], for gravity currents propagating into unstratified ambients and internal bores traveling at the interface of two-layer fluids, respectively, is extended to various well known stratified flow problems, in the following. These flows normally involve several fronts which can be analyzed according to the quasisteady conservation laws of mass and momentum by appropriate shift in the reference frame, or possibly unsteady sections for which the flow cannot be rendered quasisteady by any finite number of changes in the reference frames. The analyses of various flow components are then superimposed and matched to obtain the whole flow field. It is also demonstrated that under certain conditions the propagation of gravity currents (or intrusions) can lead to the formation of interfacial perturbations in the form of rarefaction waves or internal bores, which are a source of unsteadiness, and can substantially impact the flow dynamics as well as its energy budget.Enforcing the conservation laws for horizontal and vertical momenta concurrently, enables us to avoid employing energy-based closure assumptions invoked by previous peer models. Consequently, the assessment of flow energetics becomes plausible, which can be utilized to investigate the validity of the energy-related arguments made by other authors. Furthermore, the predictions of the current study obtained by detailed parametric studies are compared to the results of our two-dimensional direct numerical simulations as well as the theoretical and experimental findings of earlier investigations, where very good agreement is observed with regard to all flow properties.

Subjects/Keywords: Fluid mechanics; Chemical engineering; Direct Numerical Simulations; Geophysical fluid dynamics; Stratified flows; Vorticity-based modeling

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Khodkar, M. A. (2017). Vorticity-based modeling of stratified flows. (Thesis). University of California – eScholarship, University of California. Retrieved from http://www.escholarship.org/uc/item/637909vg

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Khodkar, Mohammad Amin. “Vorticity-based modeling of stratified flows.” 2017. Thesis, University of California – eScholarship, University of California. Accessed January 19, 2021. http://www.escholarship.org/uc/item/637909vg.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Khodkar, Mohammad Amin. “Vorticity-based modeling of stratified flows.” 2017. Web. 19 Jan 2021.

Vancouver:

Khodkar MA. Vorticity-based modeling of stratified flows. [Internet] [Thesis]. University of California – eScholarship, University of California; 2017. [cited 2021 Jan 19]. Available from: http://www.escholarship.org/uc/item/637909vg.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Khodkar MA. Vorticity-based modeling of stratified flows. [Thesis]. University of California – eScholarship, University of California; 2017. Available from: http://www.escholarship.org/uc/item/637909vg

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Oxford

10. Tabataba-Vakili, Fachreddin. Dynamical circulation regimes in planetary (and exo-planetary) atmospheres.

Degree: PhD, 2017, University of Oxford

URL: http://ora.ox.ac.uk/objects/uuid:0822da0e-6309-439e-b6ce-e00ff3faca75 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.740820

► In this thesis, we study the effect of diurnally- and seasonally-varying forcing on the global circulation of planetary atmospheres explored within a large parameter space.… (more)

▼ In this thesis, we study the effect of diurnally- and seasonally-varying forcing on the global circulation of planetary atmospheres explored within a large parameter space. This work focusses on studying the spacial and spectral energy budgets across a large range of planetary parameters as well as the momentum transfer as a response to diurnal and seasonal effects. We simulate planetary atmospheres using PUMA-GT, a simple GCM co-developed for this work, that is forced by a semi-grey two-band radiative-convective scheme, dissipated by Rayleigh friction and allows for temporally varying insolation. Our parameter regime includes the variation of the planetary rotation rate, frictional timescale in the boundary layer, the thermal inertia of the surface and the atmosphere, as well as the short-wave optical thickness. We calculate the energy transfer in Martian atmosphere to have a reference case of an atmosphere that is subject to very strong seasonal and diurnal variation. For this we present the first Lorenz energy budget calculated from reanalysis data of a non-Earth planet. A comparison between Martian and Earth atmosphere reveals a fundamentally different behaviour of the barotropic conversion term in the global mean. A significant impact of the thermal tide can be discerned in the generation of eddy kinetic energy, especially during global dust storms. Our study of seasonal variation reaffirms previous work that the equatorial super-rotating jet in the slow-rotating regime is arrested for strong seasonal variation. We find a novel explanation as to why the Titan atmosphere is able to maintain super-rotation despite strong surface seasonality; for non-zero short-wave absorption in the atmosphere the mechanism that hinders equatorial super-rotation is weakened. Diurnally-varying forcing can significantly enhance the equatorial super-rotation in cases with non-zero short-wave absorption. In our simulations this enhancement is maintained by a convergence of vertical momentum flux at the equator. Efforts to identify the atmospheric waves involved in this enhancement point towards thermally-excited gravity waves.

Subjects/Keywords: 551.5; geophysical fluid dynamics; radiative transfer; super-rotation; diurnal forcing; macroturbulence; planetary atmospheres; seasonal forcing

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APA (6^th Edition):

Tabataba-Vakili, F. (2017). Dynamical circulation regimes in planetary (and exo-planetary) atmospheres. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:0822da0e-6309-439e-b6ce-e00ff3faca75 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.740820

Chicago Manual of Style (16^th Edition):

Tabataba-Vakili, Fachreddin. “Dynamical circulation regimes in planetary (and exo-planetary) atmospheres.” 2017. Doctoral Dissertation, University of Oxford. Accessed January 19, 2021. http://ora.ox.ac.uk/objects/uuid:0822da0e-6309-439e-b6ce-e00ff3faca75 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.740820.

MLA Handbook (7^th Edition):

Tabataba-Vakili, Fachreddin. “Dynamical circulation regimes in planetary (and exo-planetary) atmospheres.” 2017. Web. 19 Jan 2021.

Vancouver:

Tabataba-Vakili F. Dynamical circulation regimes in planetary (and exo-planetary) atmospheres. [Internet] [Doctoral dissertation]. University of Oxford; 2017. [cited 2021 Jan 19]. Available from: http://ora.ox.ac.uk/objects/uuid:0822da0e-6309-439e-b6ce-e00ff3faca75 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.740820.

Council of Science Editors:

Tabataba-Vakili F. Dynamical circulation regimes in planetary (and exo-planetary) atmospheres. [Doctoral Dissertation]. University of Oxford; 2017. Available from: http://ora.ox.ac.uk/objects/uuid:0822da0e-6309-439e-b6ce-e00ff3faca75 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.740820

University of Colorado

11. Plumley, Meredith J. Investigations of Asymptotic Models for Convection-Driven Flows in Geophysical and Astrophysical Fluid Systems.

Degree: PhD, 2018, University of Colorado

URL: https://scholar.colorado.edu/appm_gradetds/103

► Geophysical flows, such as the turbulent motion within natural systems, are characterized by a wide range of spatial and temporal scales. Due to this… (more)

▼ Geophysical flows, such as the turbulent motion within natural systems, are characterized by a wide range of spatial and temporal scales. Due to this complexity, approaches that rely on solving the full Navier-Stokes equations are limited to values of parameters that are far from the extreme values characteristic of geophysical regimes. Therefore, results from these simulations must be extrapolated over orders of magnitude to apply to Earth's core. In this thesis, I'll present an alternative strategy for modeling these flows, which relies on deriving reduced models using asymptotic techniques. These models are investigated using efficient scientific computing methods and yield results that are within geophysically relevant parameter regimes. This thesis presents asymptotically reduced models for rapidly rotating convection in a plane layer geometry and highlights a few applications of these reduced models. Specifically, the effect of different boundary conditions on key dynamics is investigated to facilitate comparison with experimental studies. The main scientific question is if these boundary conditions are passive in geophysical parameter regimes and how the rate of rotation influences the heat flux in the systems. While direct numerical simulation and laboratory experimental results can only examine this for moderate values of rotation, the asymptotic model is applied to determine an empirical scaling for the impact of these boundary layers within the rapidly rotating regime. The dynamics of electrically conducting fluids and self-sustained magnetic fields are also investigated with the use of asymptotic models. The presence of electromagnetic fields presents added complexity in the dynamics and the use of asymptotic analysis allows us to investigate a geo/astrophysically relevant limit that is not attainable in current DNS simulations. The asymptotic reduction leads to multiple timescales that require new numerical strategies for solving and two multiscale numerical methods are tested on this new model for both single mode and multimode cases. The model is used to characterize the influence of dynamo action on convection and explore the large scale structure of the flows, especially in comparison to both non-magnetic convective results of rapidly rotating asymptotic models as well as results from dynamo simulations that are not in the geophysical parameter space. We find that dynamo action leads to fundamental changes in the dynamics, compared to non-magnetic convection, and current work is aimed at understanding the implications for natural dynamos. Advisors/Committee Members: Keith Julien, Michael A. Calkins, Ian Grooms, James Meiss, Peter Hamlington.

Subjects/Keywords: asymptotic models; fluid systems; dynamics; geophysical; astrophysical; Applied Mathematics; Geophysics and Seismology

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Plumley, M. J. (2018). Investigations of Asymptotic Models for Convection-Driven Flows in Geophysical and Astrophysical Fluid Systems. (Doctoral Dissertation). University of Colorado. Retrieved from https://scholar.colorado.edu/appm_gradetds/103

Chicago Manual of Style (16^th Edition):

Plumley, Meredith J. “Investigations of Asymptotic Models for Convection-Driven Flows in Geophysical and Astrophysical Fluid Systems.” 2018. Doctoral Dissertation, University of Colorado. Accessed January 19, 2021. https://scholar.colorado.edu/appm_gradetds/103.

MLA Handbook (7^th Edition):

Plumley, Meredith J. “Investigations of Asymptotic Models for Convection-Driven Flows in Geophysical and Astrophysical Fluid Systems.” 2018. Web. 19 Jan 2021.

Vancouver:

Plumley MJ. Investigations of Asymptotic Models for Convection-Driven Flows in Geophysical and Astrophysical Fluid Systems. [Internet] [Doctoral dissertation]. University of Colorado; 2018. [cited 2021 Jan 19]. Available from: https://scholar.colorado.edu/appm_gradetds/103.

Council of Science Editors:

Plumley MJ. Investigations of Asymptotic Models for Convection-Driven Flows in Geophysical and Astrophysical Fluid Systems. [Doctoral Dissertation]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/appm_gradetds/103

University of Toronto

12. Salehipour, Hesam. Stratified turbulence and ocean mixing.

Degree: PhD, 2017, University of Toronto

URL: http://hdl.handle.net/1807/80636

► In this thesis, I explore the complexities of stratified turbulence and its fundamental role in controlling the rate of planetary-scale ocean circulation. The thesis focuses… (more)

▼ In this thesis, I explore the complexities of stratified turbulence and its fundamental role in controlling the rate of planetary-scale ocean circulation. The thesis focuses upon two major cornerstones. The first part contributes to extend the fluid dynamical understanding associated with two archetypical instabilities in inhomogeneously stratified and sheared flows, namely (i) the Kelvin-Helmholtz instability (KHI) and (ii) the Holmboe wave instability (HWI). Direct Numerical Simulation (DNS) is employed to thoroughly analyze the growth and collapse of these instabilities in the computationally challenging, but oceanographically relevant, regime of high Reynolds and high Prandtl number. Through careful analysis of the mixing engendered by these instabilities, the intricate variations of mixing efficiency and diapycnal diffusivity with respect to various important non-dimensional parameters is investigated. Furthermore, I will introduce generalized theoretical formulations that are required for an accurate representation of the diapycnal diffusivities of mass and momentum that are required to distinguish carefully between reversible stirring and irreversible mixing. One of my key findings concerning the characterization of mixing associated with KHI is that mixing may become less efficient if turbulence is too vigorous, corroborating previous results of homogeneously stratified sheared flows and further suggesting a degree of universality in mixing properties of fully turbulent flows. Insofar as HWI is concerned, I demonstrate, for the first time, that this instability mechanism may truly become turbulent under sufficiently high Reynolds number conditions with its inertial subrange revealing a â 5/3 power-law spectral behavior that is characteristic of stratified turbulent flows. The categorical distinctions between KHI and HWI will also be discussed. Most importantly, unlike the rapid burst that characterizes the transition of KHI into turbulence, HWI will be shown to be much more long-lived due to a distinct localisation of mixing and the emergence of self-organized criticality as a characterization of the turbulence itself. The second part of this thesis applies the understanding of the stratified shear-induced turbulence developed in the first part of the thesis in the oceanographic context. I will use detailed modern measurements of ocean turbulence to establish that the â KH-ansatzâ may serve as a useful basis for the study of ocean turbulence and proceed to consolidate the results of the ensemble of KHI simulations in such a way as to propose a multi-dimensional parameterization for mixing efficiency (and thus the turbulent diapycnal diffusivities of mass and momentum). Using this proposed parameterization together with inferred dissipation rates from the Argo floats, I will present spatial maps of diapycnal mixing determined on this basis for the upper 2 km of the global oceans and will argue that current estimates of diapycnal diffusivity warrant further consideration. Furthermore, I will demonstrate… Advisors/Committee Members: Peltier, W. R., Physics.

Subjects/Keywords: geophysical fluid dynamics; mixing and dispersion; ocean circulation; stratified turbulence; wave breaking; 0415

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APA (6^th Edition):

Salehipour, H. (2017). Stratified turbulence and ocean mixing. (Doctoral Dissertation). University of Toronto. Retrieved from http://hdl.handle.net/1807/80636

Chicago Manual of Style (16^th Edition):

Salehipour, Hesam. “Stratified turbulence and ocean mixing.” 2017. Doctoral Dissertation, University of Toronto. Accessed January 19, 2021. http://hdl.handle.net/1807/80636.

MLA Handbook (7^th Edition):

Salehipour, Hesam. “Stratified turbulence and ocean mixing.” 2017. Web. 19 Jan 2021.

Vancouver:

Salehipour H. Stratified turbulence and ocean mixing. [Internet] [Doctoral dissertation]. University of Toronto; 2017. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/1807/80636.

Council of Science Editors:

Salehipour H. Stratified turbulence and ocean mixing. [Doctoral Dissertation]. University of Toronto; 2017. Available from: http://hdl.handle.net/1807/80636

Virginia Tech

13. San, Omer. Multiscale Modeling and Simulation of Turbulent Geophysical Flows.

Degree: PhD, Engineering Science and Mechanics, 2012, Virginia Tech

URL: http://hdl.handle.net/10919/28031

► The accurate and efficient numerical simulation of geophysical flows is of great interest in numerical weather prediction and climate modeling as well as in numerous… (more)

▼ The accurate and efficient numerical simulation of geophysical flows is of great interest in numerical weather prediction and climate modeling as well as in numerous critical areas and industries, such as agriculture, construction, tourism, transportation, weather-related disaster management, and sustainable energy technologies. Oceanic and atmospheric flows display an enormous range of temporal and spatial scales, from seconds to decades and from centimeters to thousands of kilometers, respectively. Scale interactions, both spatial and temporal, are the dominant feature of all aspects of general circulation models in geophysical fluid dynamics. In this thesis, to decrease the cost for these geophysical flow computations, several types of multiscale methods were systematically developed and tested for a variety of physical settings including barotropic and stratified wind-driven large scale ocean circulation models, decaying and forced two-dimensional turbulence simulations, as well as several benchmark incompressible flow problems in two and three dimensions. The new models proposed here are based on two classes of modern multiscale methods: (i) interpolation based approaches in the context of the multigrid/multiresolution methodologies, and (ii) deconvolution based spatial filtering approaches in the context of large eddy simulation techniques. In the first case, we developed a coarse-grid projection method that uses simple interpolation schemes to go between the two components of the problem, in which the solution algorithms have different levels of complexity. In the second case, the use of approximate deconvolution closure modeling strategies was implemented for large eddy simulations of large-scale turbulent geophysical flows. The numerical assessment of these approaches showed that both the coarse-grid projection and approximate deconvolution methods could represent viable tools for computing more realistic turbulent geophysical flows that provide significant increases in accuracy and computational efficiency over conventional methods. Advisors/Committee Members: Staples, Anne E. (committeechair), Stremler, Mark A. (committee member), De Vita, Raffaella (committee member), Iliescu, Traian (committee member), Ragab, Saad A. (committee member).

Subjects/Keywords: Geophysical Flows; Physical Oceanography; Multiscale Modeling; Multigrid; Large Eddy Simulation; Computational Fluid Dynamics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

San, O. (2012). Multiscale Modeling and Simulation of Turbulent Geophysical Flows. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/28031

Chicago Manual of Style (16^th Edition):

San, Omer. “Multiscale Modeling and Simulation of Turbulent Geophysical Flows.” 2012. Doctoral Dissertation, Virginia Tech. Accessed January 19, 2021. http://hdl.handle.net/10919/28031.

MLA Handbook (7^th Edition):

San, Omer. “Multiscale Modeling and Simulation of Turbulent Geophysical Flows.” 2012. Web. 19 Jan 2021.

Vancouver:

San O. Multiscale Modeling and Simulation of Turbulent Geophysical Flows. [Internet] [Doctoral dissertation]. Virginia Tech; 2012. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/10919/28031.

Council of Science Editors:

San O. Multiscale Modeling and Simulation of Turbulent Geophysical Flows. [Doctoral Dissertation]. Virginia Tech; 2012. Available from: http://hdl.handle.net/10919/28031

Princeton University

14. Momen, Mostafa. Dynamics of Atmospheric Boundary Layers: Large Eddy Simulations and Reduced Analytical Models .

Degree: PhD, 2016, Princeton University

URL: http://arks.princeton.edu/ark:/88435/dsp015m60qv38q

► Real-world atmospheric and oceanic boundary layers (ABL) involve many inherent complexities, the understanding and modeling of which manifestly exceeds our current capabilities. Previous studies largely… (more)

▼ Real-world atmospheric and oceanic boundary layers (ABL) involve many inherent complexities, the understanding and modeling of which manifestly exceeds our current capabilities. Previous studies largely focused on the “textbook ABL”, which is (quasi) steady and barotropic. However, it is evident that the “real-world ABL”, even over flat terrain, rarely meets such simplifying assumptions. The present thesis aims to illustrate and model four complicating features of ABLs that have been overlooked thus far despite their ubiquity: 1) unsteady pressure gradients in neutral ABLs (Chapters ‎2 and ‎3), 2) interacting effects of unsteady pressure gradients and static stability in diabatic ABLs (Chapter ‎4), 3) time-variable buoyancy fluxes (Chapter ‎5) , and 4) impacts of baroclinicity in neutral and diabatic ABLs (Chapter ‎6). State-of-the-art large-eddy simulations will be used as a tool to explain the underlying physics and to validate analytical models we develop for these features. Chapter ‎2 focuses on the turbulence equilibrium: when the forcing time scale is comparable to the turbulence time scale, the turbulence is shown to be out of equilibrium, and the velocity profiles depart from the log-law; However, for longer, and surprisingly for shorter forcing times, quasi-equilibrium is maintained. In Chapter ‎3, a reduced analytical model, based on the Navier-Stokes equations, will be introduced and shown to be analogous to a damped oscillator where inertial, Coriolis, and friction forces mirror the mass, spring, and damper, respectively. When a steady buoyancy (stable or unstable) is superposed on the unsteady pressure gradient, the same model structure can be maintained, but the damping term, corresponding to friction forces and vertical coupling, needs to account for stability. However, for the reverse case with variable buoyancy flux and stability, the model needs to be extended to allow time-variable damper coefficient. These extensions of the analytical model are presented respectively in Chapters ‎4 and ‎5. Chapter ‎6 investigates the interacting effects of baroclinicity (direction and strength) and stability on ABLs. Cold advection and positive shear increased the friction velocity, the low-level jet elevation and strength while warm advection and negative shear acted opposite. Finally, Chapter ‎7 provides a synthesis and a future outlook. Advisors/Committee Members: Bou-Zeid, Elie (advisor).

Subjects/Keywords: Fluid Dynamics; Geophysical Flows; Large-Eddy Simulations; Turbulence; Unsteady Pressure Gradient; Variable Buoyancy

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APA (6^th Edition):

Momen, M. (2016). Dynamics of Atmospheric Boundary Layers: Large Eddy Simulations and Reduced Analytical Models . (Doctoral Dissertation). Princeton University. Retrieved from http://arks.princeton.edu/ark:/88435/dsp015m60qv38q

Chicago Manual of Style (16^th Edition):

Momen, Mostafa. “Dynamics of Atmospheric Boundary Layers: Large Eddy Simulations and Reduced Analytical Models .” 2016. Doctoral Dissertation, Princeton University. Accessed January 19, 2021. http://arks.princeton.edu/ark:/88435/dsp015m60qv38q.

MLA Handbook (7^th Edition):

Momen, Mostafa. “Dynamics of Atmospheric Boundary Layers: Large Eddy Simulations and Reduced Analytical Models .” 2016. Web. 19 Jan 2021.

Vancouver:

Momen M. Dynamics of Atmospheric Boundary Layers: Large Eddy Simulations and Reduced Analytical Models . [Internet] [Doctoral dissertation]. Princeton University; 2016. [cited 2021 Jan 19]. Available from: http://arks.princeton.edu/ark:/88435/dsp015m60qv38q.

Council of Science Editors:

Momen M. Dynamics of Atmospheric Boundary Layers: Large Eddy Simulations and Reduced Analytical Models . [Doctoral Dissertation]. Princeton University; 2016. Available from: http://arks.princeton.edu/ark:/88435/dsp015m60qv38q

University of Cambridge

15. Atkinson, Jack William. Laminar analogues of atmospheric phenomena.

Degree: PhD, 2020, University of Cambridge

URL: https://doi.org/10.17863/CAM.49925 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.801816

► This thesis comprises a series of investigations into isolated vortices that exist within the atmosphere. It consists of numerical and experimental investigations backed up by… (more)

▼ This thesis comprises a series of investigations into isolated vortices that exist within the atmosphere. It consists of numerical and experimental investigations backed up by mathematical analysis. The main thrust of the work is in using laminar analogues of complex phenomena to aid the understanding of the key physical processes involved. The first portion of the research concerns the dynamics of eyes (regions of reversed flow) at the centres of vortices. We expand upon previous work investigating the process of eye formation in shallow rotating convection. Through a series of numerical simulations we observe that, as thermal forcing is increased, the system undergoes a Hopf bifurcation from a steady state to one in which the eye oscillates. Examining the nature of the oscillations we propose that this behaviour results from a trapped inertial wave, providing a range of evidence to support this theory. Following on from this we present a series of laboratory investigations designed to replicate our numerical studies. In addition to examining large scale circulations we also include some observations of rotating cellular convection. Though unsuccessful in generating a steady eye, our discussions of experiment design and implementation provide a number of insights, and we hope that future experimental work will build upon this preliminary study. The latter portion of the thesis is given over to the study of thermals. We consider the life cycle of an axisymmetric laminar thermal as it transitions through a number of distinct stages undergoing several morphological changes. A significant achievement of the study is to establish a mathematical framework that can be used throughout the life cycle, allowing us to shed light on the transitions between stages and address some previously unresolved questions. Our numerical results show the early stages of development to be key in determining the final properties of the buoyant vortex ring that is produced, with thermals displaying an independence above a critical Reynolds number. Another notable observation is that the wake left behind by the first vortex ring can itself roll up to form a second ring that follows after the first. It is hoped that this framework and our observations of laminar thermals might perhaps be useful in providing new approaches for studying atmospheric convection.

Subjects/Keywords: Geophysical Fluid Dynamics; Fluid Dynamics; Fluid Mechanics; Atmosphere; Vortices; Thermals; Buoyancy; Simulation; Experiment; Vortex Dynamics; Meteorology; Convection; Geophysics; Rotating Flows; Vortex Rings

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Atkinson, J. W. (2020). Laminar analogues of atmospheric phenomena. (Doctoral Dissertation). University of Cambridge. Retrieved from https://doi.org/10.17863/CAM.49925 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.801816

Chicago Manual of Style (16^th Edition):

Atkinson, Jack William. “Laminar analogues of atmospheric phenomena.” 2020. Doctoral Dissertation, University of Cambridge. Accessed January 19, 2021. https://doi.org/10.17863/CAM.49925 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.801816.

MLA Handbook (7^th Edition):

Atkinson, Jack William. “Laminar analogues of atmospheric phenomena.” 2020. Web. 19 Jan 2021.

Vancouver:

Atkinson JW. Laminar analogues of atmospheric phenomena. [Internet] [Doctoral dissertation]. University of Cambridge; 2020. [cited 2021 Jan 19]. Available from: https://doi.org/10.17863/CAM.49925 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.801816.

Council of Science Editors:

Atkinson JW. Laminar analogues of atmospheric phenomena. [Doctoral Dissertation]. University of Cambridge; 2020. Available from: https://doi.org/10.17863/CAM.49925 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.801816

University of Cambridge

16. Atkinson, Jack William. Laminar Analogues of Atmospheric Phenomena.

Degree: PhD, 2020, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/302851

► This thesis comprises a series of investigations into isolated vortices that exist within the atmosphere. It consists of numerical and experimental investigations backed up by… (more)

▼ This thesis comprises a series of investigations into isolated vortices that exist within the atmosphere. It consists of numerical and experimental investigations backed up by mathematical analysis. The main thrust of the work is in using laminar analogues of complex phenomena to aid the understanding of the key physical processes involved. The first portion of the research concerns the dynamics of eyes (regions of reversed flow) at the centres of vortices. We expand upon previous work investigating the process of eye formation in shallow rotating convection. Through a series of numerical simulations we observe that, as thermal forcing is increased, the system undergoes a Hopf bifurcation from a steady state to one in which the eye oscillates. Examining the nature of the oscillations we propose that this behaviour results from a trapped inertial wave, providing a range of evidence to support this theory. Following on from this we present a series of laboratory investigations designed to replicate our numerical studies. In addition to examining large scale circulations we also include some observations of rotating cellular convection. Though unsuccessful in generating a steady eye, our discussions of experiment design and implementation provide a number of insights, and we hope that future experimental work will build upon this preliminary study. The latter portion of the thesis is given over to the study of thermals. We consider the life cycle of an axisymmetric laminar thermal as it transitions through a number of distinct stages undergoing several morphological changes. A significant achievement of the study is to establish a mathematical framework that can be used throughout the life cycle, allowing us to shed light on the transitions between stages and address some previously unresolved questions. Our numerical results show the early stages of development to be key in determining the final properties of the buoyant vortex ring that is produced, with thermals displaying an independence above a critical Reynolds number. Another notable observation is that the wake left behind by the first vortex ring can itself roll up to form a second ring that follows after the first. It is hoped that this framework and our observations of laminar thermals might perhaps be useful in providing new approaches for studying atmospheric convection.

Subjects/Keywords: Geophysical Fluid Dynamics; Fluid Dynamics; Fluid Mechanics; Atmosphere; Vortices; Thermals; Buoyancy; Simulation; Experiment; Vortex Dynamics; Meteorology; Convection; Geophysics; Rotating Flows; Vortex Rings

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Atkinson, J. W. (2020). Laminar Analogues of Atmospheric Phenomena. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/302851

Chicago Manual of Style (16^th Edition):

Atkinson, Jack William. “Laminar Analogues of Atmospheric Phenomena.” 2020. Doctoral Dissertation, University of Cambridge. Accessed January 19, 2021. https://www.repository.cam.ac.uk/handle/1810/302851.

MLA Handbook (7^th Edition):

Atkinson, Jack William. “Laminar Analogues of Atmospheric Phenomena.” 2020. Web. 19 Jan 2021.

Vancouver:

Atkinson JW. Laminar Analogues of Atmospheric Phenomena. [Internet] [Doctoral dissertation]. University of Cambridge; 2020. [cited 2021 Jan 19]. Available from: https://www.repository.cam.ac.uk/handle/1810/302851.

Council of Science Editors:

Atkinson JW. Laminar Analogues of Atmospheric Phenomena. [Doctoral Dissertation]. University of Cambridge; 2020. Available from: https://www.repository.cam.ac.uk/handle/1810/302851

17. O'Rourke, Amanda Kathleen. Influence of Long and Short Planetary Waves on the Separation of the Eddy-Driven and Subtropical Jets .

Degree: PhD, 2015, Princeton University

URL: http://arks.princeton.edu/ark:/88435/dsp01tx31qk92s

► The interaction of the subtropical and eddy-driven jets is associated with both the internal low-frequency variability of the midlatitudes and the atmospheric response to anthropologically… (more)

Subjects/Keywords: atmospheric dynamics; geophysical fluid dynamics; jets

…to understand the dynamics of the “jet stream,” one must investigate the interplay of these… …We first begin with a short description of the independent dynamics of the subtropical and… …which suggests additional dynamics are at play. 3 1.2 The Eddy-Driven Jet As the name… …the dynamics of the zonal mean flow (Simmons et al., 1983; Kidston and Vallis, 2010…

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APA (6^th Edition):

O'Rourke, A. K. (2015). Influence of Long and Short Planetary Waves on the Separation of the Eddy-Driven and Subtropical Jets . (Doctoral Dissertation). Princeton University. Retrieved from http://arks.princeton.edu/ark:/88435/dsp01tx31qk92s

Chicago Manual of Style (16^th Edition):

O'Rourke, Amanda Kathleen. “Influence of Long and Short Planetary Waves on the Separation of the Eddy-Driven and Subtropical Jets .” 2015. Doctoral Dissertation, Princeton University. Accessed January 19, 2021. http://arks.princeton.edu/ark:/88435/dsp01tx31qk92s.

MLA Handbook (7^th Edition):

O'Rourke, Amanda Kathleen. “Influence of Long and Short Planetary Waves on the Separation of the Eddy-Driven and Subtropical Jets .” 2015. Web. 19 Jan 2021.

Vancouver:

O'Rourke AK. Influence of Long and Short Planetary Waves on the Separation of the Eddy-Driven and Subtropical Jets . [Internet] [Doctoral dissertation]. Princeton University; 2015. [cited 2021 Jan 19]. Available from: http://arks.princeton.edu/ark:/88435/dsp01tx31qk92s.

Council of Science Editors:

O'Rourke AK. Influence of Long and Short Planetary Waves on the Separation of the Eddy-Driven and Subtropical Jets . [Doctoral Dissertation]. Princeton University; 2015. Available from: http://arks.princeton.edu/ark:/88435/dsp01tx31qk92s

University of Cambridge

18. Stamper, Megan Andrena. The evolution and breakdown of submesoscale instabilities.

Degree: PhD, 2018, University of Cambridge

URL: https://doi.org/10.17863/CAM.25162 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.753329

► Ocean submesoscales are the subject of increasing focus in the oceanographic literature; with instrumentation now more capable of observing them in situ and numerical models… (more)

▼ Ocean submesoscales are the subject of increasing focus in the oceanographic literature; with instrumentation now more capable of observing them in situ and numerical models now able to reach the resolution required to more fully capture them. Submesoscales are typified by horizontal spatial scales of O(1 − 10) km, vertical scales O(100) m and time-scales of O(1) day and are known to be associated with regions of high vertical velocity and vorticity. Occurring most commonly at density fronts at the ocean surface they can control mixed layer restratification and provide an important control on fluxes between the atmosphere and the deep ocean. This thesis sets out to better understand the fundamental physical processes underpinning submesoscale instabilities using a number of idealised process models. Linear stability analysis complemented by non-linear, high-resolution simulations will be used initially to explore the ways in which submesoscale instabilities in the mixed layer may compete and interact with one another. In particular, we will investigate the way in which symmetric and ageostrophic baroclinic instabilities interact when simultaneously present in a flow, with focus on the growth rates and energetic pathways of previously unexplored dynamic instabilities that arise in this paradigm; three-dimensional, mixed symmetric-baroclinic instabilities. Further, these non-linear simulations will allow us to investigate the transition to dissipative scales that can occur in the classical Eady model via a multitude of small-scale secondary instabilities that result from primary submesoscale instabilities. Finally, observational data, taken aboard the SMILES project cruise to the Southern Ocean, helps to motivate the consideration of a new dynamical paradigm; the Eady model with superimposed high amplitude barotropic jet. Non-linear simulations investigate the extent to which the addition of such a jet is capable of damping submesoscale growth. The causes of this damping are then investigated using linear analysis. With this approach eventually demonstrated as being unable to fully explain growth rate reductions, we introduce a new framework combining potential vorticity mixing by submesoscale instabilities with geostrophic adjustment, which relaxes the flow back to a geostrophic balanced state. This framework will help to explain, conceptually, how non-linear eddies control the linear stability of the flow.

Subjects/Keywords: 551.46; submesoscales; oceanography; fluid dynamics; geophysical fluid dynamics; simulations; baroclinic instability; symmetric instability; mixed layer instabilities; ocean dynamics; Eady model; linear stability analysis; geostrophic balance; applied mathematics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Stamper, M. A. (2018). The evolution and breakdown of submesoscale instabilities. (Doctoral Dissertation). University of Cambridge. Retrieved from https://doi.org/10.17863/CAM.25162 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.753329

Chicago Manual of Style (16^th Edition):

Stamper, Megan Andrena. “The evolution and breakdown of submesoscale instabilities.” 2018. Doctoral Dissertation, University of Cambridge. Accessed January 19, 2021. https://doi.org/10.17863/CAM.25162 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.753329.

MLA Handbook (7^th Edition):

Stamper, Megan Andrena. “The evolution and breakdown of submesoscale instabilities.” 2018. Web. 19 Jan 2021.

Vancouver:

Stamper MA. The evolution and breakdown of submesoscale instabilities. [Internet] [Doctoral dissertation]. University of Cambridge; 2018. [cited 2021 Jan 19]. Available from: https://doi.org/10.17863/CAM.25162 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.753329.

Council of Science Editors:

Stamper MA. The evolution and breakdown of submesoscale instabilities. [Doctoral Dissertation]. University of Cambridge; 2018. Available from: https://doi.org/10.17863/CAM.25162 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.753329

19. Grace, Andrew. Direct Numerical Simulations of the Degeneration and Shear Instability of Large and Small Amplitude Basin Scale Internal Waves at Varied Aspect Ratios.

Degree: 2018, University of Waterloo

URL: http://hdl.handle.net/10012/13590

► This thesis presents high resolution simulations of the degeneration and shear instability of standing waves, or seiches, of varying amplitudes and aspect ratios in a… (more)

▼ This thesis presents high resolution simulations of the degeneration and shear instability of standing waves, or seiches, of varying amplitudes and aspect ratios in a continuously stratified fluid. It is well known that such waves evolve to form non–linear, dispersive wave trains under certain conditions. When the initial amplitude scaled by the upper layer depth (the dimensionless amplitude) is sufficiently large, it is possible that stratified shear instability develops, possibly at the same time as the formation of wave trains early in the evolution of the flow. While both of these physical phenomena serve to move energy from large to small scales, they are fundamentally different. The development into wave trains is non-dissipative in nature, and in the asymptotic limit of small, but finite amplitude seiches may be described by variants of the Korteweg–de–Vries (KdV) equation. Shear instability, on the other hand yields Kelvin-Helmholtz billows which in turn provide one of the basic archetypes of transition to turbulence, with greatly increased rates of mixing and viscous dissipation. Discussed is how the two phenomena vary as the aspect ratio of the tank and the height of the interface between lighter and denser fluid are changed, finding examples of cases where the two phenomena co-exist. Beginning with an expository set of examples of small amplitude seiches, the process by which a seiche changes from a traditional standing wave to a more complicated small scale set of dynamics is discussed. The results demonstrate that when the initial dimensionless amplitude is small, the seiche takes more than one oscillation period for non–linear effects to become obviously present in the flow. The small amplitude results put into context the cases where the dimensionless amplitude becomes large enough such that non–linear process occur at much earlier times and there is a competition between the formation of wave trains and stratified shear instability. A quantitative accounting for the evolution of the horizontal modewise decomposition of the kinetic energy of the system is presented along with a semi-analytical model of the evolution of the fundamental mode of the seiche. Using two well known methodologies from the literature, the evolution of the mixing dynamics of the seiche is compared from an energetic perspective and a density variability perspective which illustrates a fundamental transition that occurs as the aspect ratio is decreased. Finally, the seiche degeneration and the mixing dynamics are summarized and the most likely future directions of study are highlighted.

Subjects/Keywords: Geophysical fluid dynamics; Internal waves; Seiche

…by the total density difference, ρ0 is the reference density of the fluid and H is the… …buoyancy frequency, N 2 (z), of the fluid. Finally, panel (iii) is the first… …represented as a single curve. Here, h1 and h2 are the mean upper and lower depths of the fluid… …of wisps in the density field of the fluid. Panel (i) shows the entire domain at… …change in BPE is taken as the final value BPE of the fluid at τ = 2 minus the initial…

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Grace, A. (2018). Direct Numerical Simulations of the Degeneration and Shear Instability of Large and Small Amplitude Basin Scale Internal Waves at Varied Aspect Ratios. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/13590

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Grace, Andrew. “Direct Numerical Simulations of the Degeneration and Shear Instability of Large and Small Amplitude Basin Scale Internal Waves at Varied Aspect Ratios.” 2018. Thesis, University of Waterloo. Accessed January 19, 2021. http://hdl.handle.net/10012/13590.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Grace, Andrew. “Direct Numerical Simulations of the Degeneration and Shear Instability of Large and Small Amplitude Basin Scale Internal Waves at Varied Aspect Ratios.” 2018. Web. 19 Jan 2021.

Vancouver:

Grace A. Direct Numerical Simulations of the Degeneration and Shear Instability of Large and Small Amplitude Basin Scale Internal Waves at Varied Aspect Ratios. [Internet] [Thesis]. University of Waterloo; 2018. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/10012/13590.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Grace A. Direct Numerical Simulations of the Degeneration and Shear Instability of Large and Small Amplitude Basin Scale Internal Waves at Varied Aspect Ratios. [Thesis]. University of Waterloo; 2018. Available from: http://hdl.handle.net/10012/13590

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

20. Ball, Thomasina Verity. Modelling Viscous Flow and Elastic Deformation in Fold-Thrust Belts and Magmatic Intrusions.

Degree: PhD, 2020, University of Cambridge

URL: https://www.repository.cam.ac.uk/handle/1810/298738

► Fluid dynamics governs many phenomena on the Earth's surface and interior, from the emplacement of fluid magma, to the viscous deformation of mountain ranges on… (more)

▼ Fluid dynamics governs many phenomena on the Earth's surface and interior, from the emplacement of fluid magma, to the viscous deformation of mountain ranges on the longest time scales. Understanding these processes presents a challenge to traditional modelling techniques. However, simplifying models of the leading-order features of the flow can give insight into the dominant physical balances at play. In this dissertation I use theoretical analysis, numerical simulations, and laboratory experiments to address two geophysical processes: the formation of fold-thrust belts and the dynamics of shallow magmatic intrusions. Although geophysically distinct, these two problems both involve the interplay between viscous flow and elastic deformation and so inform the modelling of one another. Fold-thrust belts are formed at convergent margins, where accretion of weak sediments to the front of the overriding plate results in continued flexural subsidence of the underthrusting plate. In this dissertation I build a new dynamic model to investigate both the role of the thickness and material properties of the incoming sediment, and the flexure in the underthrusting plate in controlling the behaviour and evolution of fold-thrust belts. The analysis shows that the evolution of fold-thrust belts can be dominated by either gravitational spreading or vertical thickening. I apply the model to the Makran accretionary prism and the Indo-Burman Ranges, and show that for the Makran flexure is important, while in the Indo-Burman Ranges the incoming sediment thickness has a first-order control on topography. The propagation of shallow magmatic intrusions is governed by the interplay between elastically deforming sedimentary layers, the viscous flow of magma beneath, and the requirement to fracture at the front. In this dissertation I describe this process by extending the model for elastic-plated gravity currents to an axisymmetric geometry and show that adhesion (or fracture toughness) gives rise to two dynamical regimes of spreading; viscosity dominant spreading and adhesion dominant spreading. Experiments using clear, PDMS elastic sheets enable new, direct measurements of the vapour tip, and confirm the existence of spreading regimes controlled by viscosity and adhesion. I extend this laminar model of magma propagation to large mafic sills, which are thought to exhibit turbulent flow. Using a hybrid laminar-turbulent flow model I examine the transition to turbulence and show that volume fluxes several orders of magnitude above the average are required to reproduce the aspect ratios of large mafic sills measured in the field. Finally, I explore the role topographic gradients may play in driving magmatic intrusions by carrying out further experiments where the elastic sheets are inclined at an angle to the horizontal. Experimental observations show the formation of a transient head and a static tail structure with good first order comparisons to the deformation patterns of the Piton de la Fournaise flank sill intrusion.

Subjects/Keywords: Geophysical fluid dynamics; Fold-thrust belts; Convergent margins; Gravity and tectonics; Lithospheric flexure; Magmatic intrusions; Elastic deformation; Lubrication theory; Fracture; Adhesion

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APA (6^th Edition):

Ball, T. V. (2020). Modelling Viscous Flow and Elastic Deformation in Fold-Thrust Belts and Magmatic Intrusions. (Doctoral Dissertation). University of Cambridge. Retrieved from https://www.repository.cam.ac.uk/handle/1810/298738

Chicago Manual of Style (16^th Edition):

Ball, Thomasina Verity. “Modelling Viscous Flow and Elastic Deformation in Fold-Thrust Belts and Magmatic Intrusions.” 2020. Doctoral Dissertation, University of Cambridge. Accessed January 19, 2021. https://www.repository.cam.ac.uk/handle/1810/298738.

MLA Handbook (7^th Edition):

Ball, Thomasina Verity. “Modelling Viscous Flow and Elastic Deformation in Fold-Thrust Belts and Magmatic Intrusions.” 2020. Web. 19 Jan 2021.

Vancouver:

Ball TV. Modelling Viscous Flow and Elastic Deformation in Fold-Thrust Belts and Magmatic Intrusions. [Internet] [Doctoral dissertation]. University of Cambridge; 2020. [cited 2021 Jan 19]. Available from: https://www.repository.cam.ac.uk/handle/1810/298738.

Council of Science Editors:

Ball TV. Modelling Viscous Flow and Elastic Deformation in Fold-Thrust Belts and Magmatic Intrusions. [Doctoral Dissertation]. University of Cambridge; 2020. Available from: https://www.repository.cam.ac.uk/handle/1810/298738

Freie Universität Berlin

21. O'Neill, Warren. Eine thermodynamisch konsistente Formulierung der pseudo-inkompressiblen Gleichungen für atmosphärische Modellierung mit einer Erweiterung für feuchte Prozesse.

Degree: 2015, Freie Universität Berlin

URL: http://dx.doi.org/10.17169/refubium-9351

► Die Atmosphärenströme definieren sich durch Prozesse auf unterschiedlichsten zeitlichen wie räumlichen Skalen. Diese Prozesse können mit den "kompressiblen'' Navier-Stokes Gleichungen modelliert werden. Es ist anzunehmen,… (more)

Subjects/Keywords: Pseudo-incompressible equations; Geophysical Fluid Dynamics; Atmospheric Modelling; 500 Naturwissenschaften und Mathematik::510 Mathematik::518 Numerische Analysis

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APA (6^th Edition):

O'Neill, W. (2015). Eine thermodynamisch konsistente Formulierung der pseudo-inkompressiblen Gleichungen für atmosphärische Modellierung mit einer Erweiterung für feuchte Prozesse. (Thesis). Freie Universität Berlin. Retrieved from http://dx.doi.org/10.17169/refubium-9351

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

O'Neill, Warren. “Eine thermodynamisch konsistente Formulierung der pseudo-inkompressiblen Gleichungen für atmosphärische Modellierung mit einer Erweiterung für feuchte Prozesse.” 2015. Thesis, Freie Universität Berlin. Accessed January 19, 2021. http://dx.doi.org/10.17169/refubium-9351.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

O'Neill, Warren. “Eine thermodynamisch konsistente Formulierung der pseudo-inkompressiblen Gleichungen für atmosphärische Modellierung mit einer Erweiterung für feuchte Prozesse.” 2015. Web. 19 Jan 2021.

Vancouver:

O'Neill W. Eine thermodynamisch konsistente Formulierung der pseudo-inkompressiblen Gleichungen für atmosphärische Modellierung mit einer Erweiterung für feuchte Prozesse. [Internet] [Thesis]. Freie Universität Berlin; 2015. [cited 2021 Jan 19]. Available from: http://dx.doi.org/10.17169/refubium-9351.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

O'Neill W. Eine thermodynamisch konsistente Formulierung der pseudo-inkompressiblen Gleichungen für atmosphärische Modellierung mit einer Erweiterung für feuchte Prozesse. [Thesis]. Freie Universität Berlin; 2015. Available from: http://dx.doi.org/10.17169/refubium-9351

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Plymouth

22. Wobus, Fred. The dynamics of dense water cascades : from laboratory scales to the Arctic Ocean.

Degree: PhD, 2013, University of Plymouth

URL: http://hdl.handle.net/10026.1/1610

► The sinking of dense shelf waters down the continental slope (or “cascading”) contributes to oceanic water mass formation and carbon cycling. Cascading is therefore of… (more)

▼ The sinking of dense shelf waters down the continental slope (or “cascading”) contributes to oceanic water mass formation and carbon cycling. Cascading is therefore of significant importance for the global overturning circulation and thus climate. The occurrence of cascades is highly intermittent in space and time and observations of the process itself (rather than its outcomes) are scarce. Global climate models do not typically resolve cascading owing to numerical challenges concerning turbulence, mixing and faithful representation of bottom boundary layer dynamics. This work was motivated by the need to improve the representation of cascading in numerical ocean circulation models. Typical 3-D hydrostatic ocean circulation models are employed in a series of numerical experiments to investigate the process of dense water cascading in both idealised and realistic model setups. Cascading on steep bottom topography is modelled using POLCOMS, a 3-D ocean circulation model using a terrain-following s-coordinate system. The model setup is based on a laboratory experiment of a continuous dense water flow from a central source on a conical slope in a rotating tank. The descent of the dense flow as characterised by the length of the plume as a function of time is studied for a range of parameters, such as density difference, speed of rotation, flow rate and (in the model) diffusivity and viscosity. Very good agreement between the model and the laboratory results is shown in dimensional and non-dimensional variables. It is confirmed that a hydrostatic model is capable of reproducing the essential physics of cascading on a very steep slope if the model correctly resolves velocity veering in the bottom boundary layer. Experiments changing the height of the bottom Ekman layer (by changing viscosity) and modifying the plume from a 2-layer system to a stratified regime (by enhancing diapycnal diffusion) confirm previous theories, demonstrate their limitations and offer new insights into the dynamics of cascading outside of the controlled laboratory conditions. In further numerical experiments, the idealised geometry of the conical slope is retained but up-scaled to oceanic dimensions. The NEMO-SHELF model is used to study the fate of a dense water plume of similar properties to the overflow of brine-enriched shelf waters from the Storfjorden in Svalbard. The overflow plume, resulting from sea ice formation in the Storfjorden polynya, cascades into the ambient stratification resembling the predominant water masses of Fram Strait. At intermediate depths between 200-500m the plume encounters a layer of warm, saline AtlanticWater. In some years the plume ‘pierces’ the Atlantic Layer and sinks into the deep Fram Strait while in other years it remains ‘arrested’ at Atlantic Layer depths. It has been unclear what parameters control whether the plume pierces the Atlantic Layer or not. In a series of experiments we vary the salinity ‘S’ and the flow rate ‘Q’ of the simulated Storfjorden overflow to investigate both strong and weak cascading…

Subjects/Keywords: 551.46; numerical modelling; dense water cascading; gravity currents; ocean circulation; geophysical fluid dynamics; Arctic Ocean; Svalbard; Spitsbergen; tidal mixing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Wobus, F. (2013). The dynamics of dense water cascades : from laboratory scales to the Arctic Ocean. (Doctoral Dissertation). University of Plymouth. Retrieved from http://hdl.handle.net/10026.1/1610

Chicago Manual of Style (16^th Edition):

Wobus, Fred. “The dynamics of dense water cascades : from laboratory scales to the Arctic Ocean.” 2013. Doctoral Dissertation, University of Plymouth. Accessed January 19, 2021. http://hdl.handle.net/10026.1/1610.

MLA Handbook (7^th Edition):

Wobus, Fred. “The dynamics of dense water cascades : from laboratory scales to the Arctic Ocean.” 2013. Web. 19 Jan 2021.

Vancouver:

Wobus F. The dynamics of dense water cascades : from laboratory scales to the Arctic Ocean. [Internet] [Doctoral dissertation]. University of Plymouth; 2013. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/10026.1/1610.

Council of Science Editors:

Wobus F. The dynamics of dense water cascades : from laboratory scales to the Arctic Ocean. [Doctoral Dissertation]. University of Plymouth; 2013. Available from: http://hdl.handle.net/10026.1/1610

23. Dubinkina, Svetlana. Statistical Mechanics and Numerical Modelling of Geophysical Fluid Dynamics.

Degree: 2010, NARCIS

URL: https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; urn:isbn:978-90-90-25310-7 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082

Subjects/Keywords: numerical analysis; conservative discretizations; statistical mechanics; geophysical fluid dynamics

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Dubinkina, S. (2010). Statistical Mechanics and Numerical Modelling of Geophysical Fluid Dynamics. (Doctoral Dissertation). NARCIS. Retrieved from https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; urn:isbn:978-90-90-25310-7 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082

Chicago Manual of Style (16^th Edition):

Dubinkina, Svetlana. “Statistical Mechanics and Numerical Modelling of Geophysical Fluid Dynamics.” 2010. Doctoral Dissertation, NARCIS. Accessed January 19, 2021. https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; urn:isbn:978-90-90-25310-7 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082.

MLA Handbook (7^th Edition):

Dubinkina, Svetlana. “Statistical Mechanics and Numerical Modelling of Geophysical Fluid Dynamics.” 2010. Web. 19 Jan 2021.

Vancouver:

Dubinkina S. Statistical Mechanics and Numerical Modelling of Geophysical Fluid Dynamics. [Internet] [Doctoral dissertation]. NARCIS; 2010. [cited 2021 Jan 19]. Available from: https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; urn:isbn:978-90-90-25310-7 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082.

Council of Science Editors:

Dubinkina S. Statistical Mechanics and Numerical Modelling of Geophysical Fluid Dynamics. [Doctoral Dissertation]. NARCIS; 2010. Available from: https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082 ; urn:NBN:nl:ui:18-17082 ; urn:isbn:978-90-90-25310-7 ; urn:NBN:nl:ui:18-17082 ; https://ir.cwi.nl/pub/17082

University of Cambridge

24. Ball, Thomasina Verity. Modelling viscous flow and elastic deformation in fold-thrust belts and magmatic intrusions.

Degree: PhD, 2020, University of Cambridge

URL: https://doi.org/10.17863/CAM.45794 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.793051

► Fluid dynamics governs many phenomena on the Earth's surface and interior, from the emplacement of fluid magma, to the viscous deformation of mountain ranges on… (more)

▼ Fluid dynamics governs many phenomena on the Earth's surface and interior, from the emplacement of fluid magma, to the viscous deformation of mountain ranges on the longest time scales. Understanding these processes presents a challenge to traditional modelling techniques. However, simplifying models of the leading-order features of the flow can give insight into the dominant physical balances at play. In this dissertation I use theoretical analysis, numerical simulations, and laboratory experiments to address two geophysical processes: the formation of fold-thrust belts and the dynamics of shallow magmatic intrusions. Although geophysically distinct, these two problems both involve the interplay between viscous flow and elastic deformation and so inform the modelling of one another. Fold-thrust belts are formed at convergent margins, where accretion of weak sediments to the front of the overriding plate results in continued flexural subsidence of the underthrusting plate. In this dissertation I build a new dynamic model to investigate both the role of the thickness and material properties of the incoming sediment, and the flexure in the underthrusting plate in controlling the behaviour and evolution of fold-thrust belts. The analysis shows that the evolution of fold-thrust belts can be dominated by either gravitational spreading or vertical thickening. I apply the model to the Makran accretionary prism and the Indo-Burman Ranges, and show that for the Makran flexure is important, while in the Indo-Burman Ranges the incoming sediment thickness has a first-order control on topography. The propagation of shallow magmatic intrusions is governed by the interplay between elastically deforming sedimentary layers, the viscous flow of magma beneath, and the requirement to fracture at the front. In this dissertation I describe this process by extending the model for elastic-plated gravity currents to an axisymmetric geometry and show that adhesion (or fracture toughness) gives rise to two dynamical regimes of spreading; viscosity dominant spreading and adhesion dominant spreading. Experiments using clear, PDMS elastic sheets enable new, direct measurements of the vapour tip, and confirm the existence of spreading regimes controlled by viscosity and adhesion. I extend this laminar model of magma propagation to large mafic sills, which are thought to exhibit turbulent flow. Using a hybrid laminar-turbulent flow model I examine the transition to turbulence and show that volume fluxes several orders of magnitude above the average are required to reproduce the aspect ratios of large mafic sills measured in the field. Finally, I explore the role topographic gradients may play in driving magmatic intrusions by carrying out further experiments where the elastic sheets are inclined at an angle to the horizontal. Experimental observations show the formation of a transient head and a static tail structure with good first order comparisons to the deformation patterns of the Piton de la Fournaise flank sill intrusion.

Subjects/Keywords: Geophysical fluid dynamics; Fold-thrust belts; Convergent margins; Gravity and tectonics; Lithospheric flexure; Magmatic intrusions; Elastic deformation; Lubrication theory; Fracture; Adhesion

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ball, T. V. (2020). Modelling viscous flow and elastic deformation in fold-thrust belts and magmatic intrusions. (Doctoral Dissertation). University of Cambridge. Retrieved from https://doi.org/10.17863/CAM.45794 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.793051

Chicago Manual of Style (16^th Edition):

Ball, Thomasina Verity. “Modelling viscous flow and elastic deformation in fold-thrust belts and magmatic intrusions.” 2020. Doctoral Dissertation, University of Cambridge. Accessed January 19, 2021. https://doi.org/10.17863/CAM.45794 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.793051.

MLA Handbook (7^th Edition):

Ball, Thomasina Verity. “Modelling viscous flow and elastic deformation in fold-thrust belts and magmatic intrusions.” 2020. Web. 19 Jan 2021.

Vancouver:

Ball TV. Modelling viscous flow and elastic deformation in fold-thrust belts and magmatic intrusions. [Internet] [Doctoral dissertation]. University of Cambridge; 2020. [cited 2021 Jan 19]. Available from: https://doi.org/10.17863/CAM.45794 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.793051.

Council of Science Editors:

Ball TV. Modelling viscous flow and elastic deformation in fold-thrust belts and magmatic intrusions. [Doctoral Dissertation]. University of Cambridge; 2020. Available from: https://doi.org/10.17863/CAM.45794 ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.793051

University of Oxford

25. Warneford, Emma S. The thermal shallow water equations, their quasi-geostrophic limit, and equatorial super-rotation in Jovian atmospheres.

Degree: PhD, 2014, University of Oxford

URL: http://ora.ox.ac.uk/objects/uuid:6604fcac-afe6-4abe-8a6f-6a09de4f933f ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618532

► Observations of Jupiter show a super-rotating (prograde) equatorial jet that has persisted for decades. Shallow water simulations run in the Jovian parameter regime reproduce the… (more)

▼ Observations of Jupiter show a super-rotating (prograde) equatorial jet that has persisted for decades. Shallow water simulations run in the Jovian parameter regime reproduce the mixture of robust vortices and alternating zonal jets observed on Jupiter, but the equatorial jet is invariably sub-rotating (retrograde). Recent work has obtained super-rotating equatorial jets by extending the standard shallow water equations to relax the height field towards its mean value. This Newtonian cooling-like term is intended to model radiative cooling to space, but its addition breaks key conservation properties for mass and momentum. In this thesis the radiatively damped thermal shallow water equations are proposed as an alternative model for Jovian atmospheres. They extend standard shallow water theory by permitting horizontal variations of the thermodynamic properties of the fluid. The additional temperature equation allows a Newtonian cooling term to be included while conserving mass and momentum. Simulations reproduce equatorial jets in the correct directions for both Jupiter and Neptune (which sub-rotates). Quasi-geostrophic theory filters out rapidly moving inertia-gravity waves. A local quasi-geostrophic theory of the radiatively damped thermal shallow water equations is derived, and then extended to cover whole planets. Simulations of this global thermal quasi-geostrophic theory show the same transition, from sub- to super-rotating equatorial jets, seen in simulations of the original thermal shallow water model as the radiative time scale is decreased. Thus the mechanism responsible for setting the direction of the equatorial jet must exist within quasi-geostrophic theory. Such a mechanism is developed by calculating the competing effects of Newtonian cooling and Rayleigh friction upon the zonal mean zonal acceleration induced by equatorially trapped Rossby waves. These waves transport no momentum in the absence of dissipation. Dissipation by Newtonian cooling creates an eastward zonal mean zonal acceleration, consistent with the formation of super-rotating equatorial jets in simulations, while the corresponding acceleration is westward for dissipation by Rayleigh friction.

Subjects/Keywords: 532; Mathematics; Fluid mechanics (mathematics); Geophysics (mathematics); geophysical fluid dynamics; computational applied mathematics; Hamiltonian mechanics; asymptotic analysis; thermal shallow water equations; Jupiter; zonal jets

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Warneford, E. S. (2014). The thermal shallow water equations, their quasi-geostrophic limit, and equatorial super-rotation in Jovian atmospheres. (Doctoral Dissertation). University of Oxford. Retrieved from http://ora.ox.ac.uk/objects/uuid:6604fcac-afe6-4abe-8a6f-6a09de4f933f ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618532

Chicago Manual of Style (16^th Edition):

Warneford, Emma S. “The thermal shallow water equations, their quasi-geostrophic limit, and equatorial super-rotation in Jovian atmospheres.” 2014. Doctoral Dissertation, University of Oxford. Accessed January 19, 2021. http://ora.ox.ac.uk/objects/uuid:6604fcac-afe6-4abe-8a6f-6a09de4f933f ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618532.

MLA Handbook (7^th Edition):

Warneford, Emma S. “The thermal shallow water equations, their quasi-geostrophic limit, and equatorial super-rotation in Jovian atmospheres.” 2014. Web. 19 Jan 2021.

Vancouver:

Warneford ES. The thermal shallow water equations, their quasi-geostrophic limit, and equatorial super-rotation in Jovian atmospheres. [Internet] [Doctoral dissertation]. University of Oxford; 2014. [cited 2021 Jan 19]. Available from: http://ora.ox.ac.uk/objects/uuid:6604fcac-afe6-4abe-8a6f-6a09de4f933f ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618532.

Council of Science Editors:

Warneford ES. The thermal shallow water equations, their quasi-geostrophic limit, and equatorial super-rotation in Jovian atmospheres. [Doctoral Dissertation]. University of Oxford; 2014. Available from: http://ora.ox.ac.uk/objects/uuid:6604fcac-afe6-4abe-8a6f-6a09de4f933f ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618532

University of Colorado

26. Chen, Amy. Analyzing Lagrangian Statistics of Eddy-Permitting Models.

Degree: MS, Applied Mathematics, 2018, University of Colorado

URL: https://scholar.colorado.edu/appm_gradetds/98

► Mesoscale eddies are the strongest currents in the world oceans and transport properties such as heat, dissolved nutrients, and carbon. The current inability to… (more)

Subjects/Keywords: eddy-permitting models; mesoscale eddies; geophysical fluid dynamics; Lagrangian statistics; physical oceanography; numerical analysis; Dynamic Systems; Numerical Analysis and Computation; Ordinary Differential Equations and Applied Dynamics

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Chen, A. (2018). Analyzing Lagrangian Statistics of Eddy-Permitting Models. (Masters Thesis). University of Colorado. Retrieved from https://scholar.colorado.edu/appm_gradetds/98

Chicago Manual of Style (16^th Edition):

Chen, Amy. “Analyzing Lagrangian Statistics of Eddy-Permitting Models.” 2018. Masters Thesis, University of Colorado. Accessed January 19, 2021. https://scholar.colorado.edu/appm_gradetds/98.

MLA Handbook (7^th Edition):

Chen, Amy. “Analyzing Lagrangian Statistics of Eddy-Permitting Models.” 2018. Web. 19 Jan 2021.

Vancouver:

Chen A. Analyzing Lagrangian Statistics of Eddy-Permitting Models. [Internet] [Masters thesis]. University of Colorado; 2018. [cited 2021 Jan 19]. Available from: https://scholar.colorado.edu/appm_gradetds/98.

Council of Science Editors:

Chen A. Analyzing Lagrangian Statistics of Eddy-Permitting Models. [Masters Thesis]. University of Colorado; 2018. Available from: https://scholar.colorado.edu/appm_gradetds/98

University of Michigan

27. Kao, Kuo-Cheng. Computational methods for multi-domain geophysical flows.

Degree: PhD, Geophysics, 2006, University of Michigan

URL: http://hdl.handle.net/2027.42/126459

► Approximate methods for multi-domain computation of incompressible flows with a free surface are developed and tested. A semi-implicit model is constructed and applied to the… (more)

Subjects/Keywords: Computational Fluid Dynamics; Domain; Geophysical Flows; Multi; Numerical Methods; Receding Boundary Method

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APA (6^th Edition):

Kao, K. (2006). Computational methods for multi-domain geophysical flows. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/126459

Chicago Manual of Style (16^th Edition):

Kao, Kuo-Cheng. “Computational methods for multi-domain geophysical flows.” 2006. Doctoral Dissertation, University of Michigan. Accessed January 19, 2021. http://hdl.handle.net/2027.42/126459.

MLA Handbook (7^th Edition):

Kao, Kuo-Cheng. “Computational methods for multi-domain geophysical flows.” 2006. Web. 19 Jan 2021.

Vancouver:

Kao K. Computational methods for multi-domain geophysical flows. [Internet] [Doctoral dissertation]. University of Michigan; 2006. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/2027.42/126459.

Council of Science Editors:

Kao K. Computational methods for multi-domain geophysical flows. [Doctoral Dissertation]. University of Michigan; 2006. Available from: http://hdl.handle.net/2027.42/126459

28. Ogbonna, Christian Chukwuebuka. Non-linear Interactions between Internal Wave Beams: Beyond the Traditional Approximation.

Degree: 2017, University of Waterloo

URL: http://hdl.handle.net/10012/12438

► The problem of nonlinear interactions of internal waves is solved using small-amplitude expansions beyond the traditional approximation; that is the horizontal component of the Earth’s… (more)

Subjects/Keywords: Geophysical Fluid Dynamics; Internal Gravity Waves; Small amplitude expansion

…Approximation The term hydrostatic approximation is a concept in geophysical fluid dynamics that is… …16 A coordinate system with the x-z axis rotated counterclockwise by an angle φ, the fluid… …x28;nonlinear) internal gravity-wave beams in a uniformly stratified Boussinesq fluid… …significantly changes the dynamics of near-inertial waves for weak stratification in a vertically… …when this law is applied to a mass of fluid, it gives the momentum equation which governs…

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APA (6^th Edition):

Ogbonna, C. C. (2017). Non-linear Interactions between Internal Wave Beams: Beyond the Traditional Approximation. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/12438

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Ogbonna, Christian Chukwuebuka. “Non-linear Interactions between Internal Wave Beams: Beyond the Traditional Approximation.” 2017. Thesis, University of Waterloo. Accessed January 19, 2021. http://hdl.handle.net/10012/12438.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Ogbonna, Christian Chukwuebuka. “Non-linear Interactions between Internal Wave Beams: Beyond the Traditional Approximation.” 2017. Web. 19 Jan 2021.

Vancouver:

Ogbonna CC. Non-linear Interactions between Internal Wave Beams: Beyond the Traditional Approximation. [Internet] [Thesis]. University of Waterloo; 2017. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/10012/12438.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ogbonna CC. Non-linear Interactions between Internal Wave Beams: Beyond the Traditional Approximation. [Thesis]. University of Waterloo; 2017. Available from: http://hdl.handle.net/10012/12438

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

29. Tangarife, Tomás. Théorie cinétique et grandes déviations en dynamique des fluides géophysiques : Kinetic theory and large deviations for the dynamics of geophysical flows.

Degree: Docteur es, Physique, 2015, Lyon, École normale supérieure

URL: http://www.theses.fr/2015ENSL1037

►

Cette thèse porte sur la dynamique des grandes échelles des écoulements géophysiques turbulents, en particulier sur leur organisation en écoulements parallèles orientés dans la direction… (more)

▼

Cette thèse porte sur la dynamique des grandes échelles des écoulements géophysiques turbulents, en particulier sur leur organisation en écoulements parallèles orientés dans la direction est-ouest (jets zonaux). Ces structures ont la particularité d'évoluer sur des périodes beaucoup plus longues que la turbulence qui les entoure. D'autre part, on observe dans certains cas, sur ces échelles de temps longues, des transitions brutales entre différentes configurations des jets zonaux (multistabilité). L'approche proposée dans cette thèse consiste à moyenner l'effet des degrés de liberté turbulents rapides de manière à obtenir une description effective des grandes échelles spatiales de l'écoulement, en utilisant les outils de moyennisation stochastique et la théorie des grandes déviations. Ces outils permettent d'étudier à la fois les attracteurs, les fluctuations typiques et les fluctuations extrêmes de la dynamique des jets. Cela permet d'aller au-delà des approches antérieures, qui ne décrivent que le comportement moyen des jets.Le premier résultat est une équation effective pour la dynamique lente des jets, la validité de cette équation est étudiée d'un point de vue théorique, et les conséquences physiques sont discutées. De manière à décrire la statistique des évènements rares tels que les transitions brutales entre différentes configurations des jets, des outils issus de la théorie des grandes déviations sont employés. Des méthodes originales sont développées pour mettre en œuvre cette théorie, ces méthodes peuvent par exemple être appliquées à des situations de multistabilité.

This thesis deals with the dynamics of geophysical turbulent flows at large scales, more particularly their organization into east-west parallel flows (zonal jets). These structures have the particularity to evolve much slower than the surrounding turbulence. Besides, over long time scales, abrupt transitions between different configurations of zonal jets are observed in some cases (multistability). Our approach consists in averaging the effect of fast turbulent degrees of freedom in order to obtain an effective description of the large scales of the flow, using stochastic averaging and the theory of large deviations. These tools provide theattractors, the typical fluctuations and the large fluctuations of jet dynamics. This allows to go beyond previous studies, which only describe the average jet dynamics. Our first result is an effective equation for the slow dynamics of jets, the validityof this equation is studied from a theoretical point of view, and the physical consequences are discussed. In order to describe the statistics of rare events such as abrupt transitions between different jet configurations, tools from large deviation theory are employed. Original methods are developped in order to implement this theory, those methods can be applied for instance in situations of multistability.

Advisors/Committee Members: Bouchet, Freddy (thesis director).

Subjects/Keywords: Dynamique des fluides géophysiques; Jets zonaux; Moyennisation stochastique; Théorie des grandes déviations; Geophysical fluid dynamics; Zonal jets; Stochastic averaging; Large deviation theory

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Tangarife, T. (2015). Théorie cinétique et grandes déviations en dynamique des fluides géophysiques : Kinetic theory and large deviations for the dynamics of geophysical flows. (Doctoral Dissertation). Lyon, École normale supérieure. Retrieved from http://www.theses.fr/2015ENSL1037

Chicago Manual of Style (16^th Edition):

Tangarife, Tomás. “Théorie cinétique et grandes déviations en dynamique des fluides géophysiques : Kinetic theory and large deviations for the dynamics of geophysical flows.” 2015. Doctoral Dissertation, Lyon, École normale supérieure. Accessed January 19, 2021. http://www.theses.fr/2015ENSL1037.

MLA Handbook (7^th Edition):

Tangarife, Tomás. “Théorie cinétique et grandes déviations en dynamique des fluides géophysiques : Kinetic theory and large deviations for the dynamics of geophysical flows.” 2015. Web. 19 Jan 2021.

Vancouver:

Tangarife T. Théorie cinétique et grandes déviations en dynamique des fluides géophysiques : Kinetic theory and large deviations for the dynamics of geophysical flows. [Internet] [Doctoral dissertation]. Lyon, École normale supérieure; 2015. [cited 2021 Jan 19]. Available from: http://www.theses.fr/2015ENSL1037.

Council of Science Editors:

Tangarife T. Théorie cinétique et grandes déviations en dynamique des fluides géophysiques : Kinetic theory and large deviations for the dynamics of geophysical flows. [Doctoral Dissertation]. Lyon, École normale supérieure; 2015. Available from: http://www.theses.fr/2015ENSL1037

30. Owen, A. Resonant effects in weakly nonlinear geophysical fluid dynamics.

Degree: PhD, 2019, University of Exeter

URL: http://hdl.handle.net/10871/37703

► Many observed phenomena in geophysical systems, such as quasigeostrophy, and turbulence effects in rotating fluids, can be attributed to the resonances that emerge from multiple… (more)

▼ Many observed phenomena in geophysical systems, such as quasigeostrophy, and turbulence effects in rotating fluids, can be attributed to the resonances that emerge from multiple scale analysis. In this thesis the multiple scale method of asymptotic expansion is used to study resonant wave interactions in the context of quasigeostrophic geophysical systems, including and extending triad interactions. The one and two layer rotating shallow water equations and the equations for uniformly stratified fluid under the Boussinesq assumption are studied in detail, we evaluate their asymptotic expansions, and analyse their behaviour. Of particular interest is the expansion for the two layer equations, where we investigate a resonance not previously considered in the literature. We formulate general theory concerning the behaviour of the splitting of the dynamics into the fast and slow parts of the systems. We find that all layered shallow water type equations cannot have any interaction between a set of fast waves that produces a slow wave, regardless of whether they are resonant or non-resonant. In the stratified case we find that this is not true, although these interactions are constrained to a slow timescale. Building on the resonant expansion, we then reformulate the expansions to allow the inclusion of near resonant interactions. We detail a new formulation of the near resonances as the representation of higher order interactions that are sufficiently fast acting to be included at the triad order of interaction. We then demonstrate the effectiveness of this near resonant expansion by direct numerical simulation and evaluation of the rotating shallow water equations. We derive qualitatively different behaviour, found analytically in the near resonant expansion of the stratified equations, showing that many higher order interactions not accessible in the layered equations are possible in the stratified case. Finally we consider the expansions in the wavepacket framework, with the introduction of multiple spatial scales. We find that consideration of the magnitude of the difference between the group velocities of component wavepackets in a quartet interaction is sufficient to derive the higher order behaviour previously found by other methods in the literature. It then follows from this that the near resonant expansion can contain many types of interaction that are not possible between wavepackets if only exact resonances are considered.

Subjects/Keywords: 510; Geophysical fluid dynamics; weakly nonlinear fluids; near resonance

…geophysical fluid dynamics. These systems will be introduced in chapter 2. Some new results in the… …ideas of near and exact resonances will be explored in the context of geophysical fluid… …fluid dynamics and are derived from the incompressible Euler equations. A general derivation… …Equations of Motion In this chapter the main geophysical fluid systems in the thesis are derived… …nonlinear combinations that contribute to the dynamics on that timescale, while non-resonances can…

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APA (6^th Edition):

Owen, A. (2019). Resonant effects in weakly nonlinear geophysical fluid dynamics. (Doctoral Dissertation). University of Exeter. Retrieved from http://hdl.handle.net/10871/37703

Chicago Manual of Style (16^th Edition):

Owen, A. “Resonant effects in weakly nonlinear geophysical fluid dynamics.” 2019. Doctoral Dissertation, University of Exeter. Accessed January 19, 2021. http://hdl.handle.net/10871/37703.

MLA Handbook (7^th Edition):

Owen, A. “Resonant effects in weakly nonlinear geophysical fluid dynamics.” 2019. Web. 19 Jan 2021.

Vancouver:

Owen A. Resonant effects in weakly nonlinear geophysical fluid dynamics. [Internet] [Doctoral dissertation]. University of Exeter; 2019. [cited 2021 Jan 19]. Available from: http://hdl.handle.net/10871/37703.

Council of Science Editors:

Owen A. Resonant effects in weakly nonlinear geophysical fluid dynamics. [Doctoral Dissertation]. University of Exeter; 2019. Available from: http://hdl.handle.net/10871/37703

Open Access Theses and Dissertations