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You searched for subject:(incomplete mixing). Showing records 1 – 3 of 3 total matches.

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Universiteit Utrecht

1. Pit, I.R. Incomplete mixing of soil water in the H.J. Andrews Experimental Forest. A modeling study of water and nitrogen fluxes on a hillslope.

Degree: 2011, Universiteit Utrecht

Hillslope hydrology involves the examination of processes in the soil that influences water flowing downslope. A consensus on how water is displaced on hillslopes is still lacking, because processes involved with hillslope hydrology are difficult to observe and understand. This master thesis included a model study to estimate if incomplete mixing of soil water is present on a hillslope. Therefore a biogeochemistry-hydrological model is used, that is parameterized with data of a trenched hillslope in a headwater catchment (WS10) in the H.J. Andrews Experimental Forest (OR, USA). With the use of quantitative and qualitative (nitrogen) measures of water transport through the hillslope, two model simulations were compared. Model simulation 1 contains only complete mixing of inorganic nitrogen and model simulation 2 contains both incomplete and complete mixing of inorganic nitrogen. By comparing the results of model simulations 1 and 2 there is no clear evidence that incomplete mixing of inorganic nitrogen occurs on the hillslope. Besides model improvements, future research could include improving the dataset of nitrogen measurements, a tighter linkage between vegetation and hydrology by incorporating actual transpiration rates and a focus on both nitrogen and water-isotopes. Advisors/Committee Members: Rebel, K.T..

Subjects/Keywords: Geowetenschappen; hillslope hydrology; nitrogen; WALNUTS; ecohydrology; incomplete mixing; succession

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APA (6th Edition):

Pit, I. R. (2011). Incomplete mixing of soil water in the H.J. Andrews Experimental Forest. A modeling study of water and nitrogen fluxes on a hillslope. (Masters Thesis). Universiteit Utrecht. Retrieved from http://dspace.library.uu.nl:8080/handle/1874/216328

Chicago Manual of Style (16th Edition):

Pit, I R. “Incomplete mixing of soil water in the H.J. Andrews Experimental Forest. A modeling study of water and nitrogen fluxes on a hillslope.” 2011. Masters Thesis, Universiteit Utrecht. Accessed July 07, 2020. http://dspace.library.uu.nl:8080/handle/1874/216328.

MLA Handbook (7th Edition):

Pit, I R. “Incomplete mixing of soil water in the H.J. Andrews Experimental Forest. A modeling study of water and nitrogen fluxes on a hillslope.” 2011. Web. 07 Jul 2020.

Vancouver:

Pit IR. Incomplete mixing of soil water in the H.J. Andrews Experimental Forest. A modeling study of water and nitrogen fluxes on a hillslope. [Internet] [Masters thesis]. Universiteit Utrecht; 2011. [cited 2020 Jul 07]. Available from: http://dspace.library.uu.nl:8080/handle/1874/216328.

Council of Science Editors:

Pit IR. Incomplete mixing of soil water in the H.J. Andrews Experimental Forest. A modeling study of water and nitrogen fluxes on a hillslope. [Masters Thesis]. Universiteit Utrecht; 2011. Available from: http://dspace.library.uu.nl:8080/handle/1874/216328


University of Wollongong

2. Msmali, Ahmed Hussein O. The effect of incomplete mixing in biological and chemical reactors.

Degree: PhD, 2013, University of Wollongong

Many process in chemical engineering occur in a flow reactor. When this reactor is well-mixed then the chemical process occurring within it are modeled by a system of ordinary differential equations. By ‘well-mixed’, it is meant that the concentration of a chemical at any point within the reactor is identical to that at any other point within the reactor. This is usually a good expectation for a small reactor, but it does not always hold true for industrial reactors where the reactor may be very large. In this thesis I investigate how incomplete, or poor, mixing effects the performance of a number of chemical and biochemical processes. To model the effects of incomplete mixing a segregated reactor model is used in which the reactor volume is split into two compartments: one component represents a highly agitated region whereas the other component represents a stagnant region. The number of equations for the incomplete mixing model is twice that for the ideal bioreactor model. The incomplete mixing model has two parameters. The first represents the relative volume of the stagnant region to the total volume and the second represents the degree of mixing between the two regions. Although this model was originally proposed over 40 years ago, it has not been investigated in detail. I apply it to a variety of chemical mechanisms in the fields of bioreactor engineering and non-linear chemical dynamics. The former are the Monod model and a model for a membrane-coupled anaerobic fermentor. The latter are the Belousov-Zhabotinskii reaction and a model for quadratic autocatalysis with a non-linear decay term. The main technique used for both the ‘perfect mixing’ and ‘imperfect mixing’ reactor models is to find the steady-state solutions and determine their stability as a function of the residence time, which is the main experimental control parameter. We find that the effect of incomplete mixing can not be to remove a transcritical bifurcation at which a washout branch loses stability. However it does change the value of the residence time at which the transition occurs. For other bifurcation the effect of incomplete mixing may be more significant. Both static and dynamic bifurcations can be eliminated by poor mixing.

Subjects/Keywords: incomplete mixing; Belousov-Zhabotinskii reaction; membrane; autocatalytic; singularity theory

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APA (6th Edition):

Msmali, A. H. O. (2013). The effect of incomplete mixing in biological and chemical reactors. (Doctoral Dissertation). University of Wollongong. Retrieved from ; https://ro.uow.edu.au/theses/4061

Chicago Manual of Style (16th Edition):

Msmali, Ahmed Hussein O. “The effect of incomplete mixing in biological and chemical reactors.” 2013. Doctoral Dissertation, University of Wollongong. Accessed July 07, 2020. ; https://ro.uow.edu.au/theses/4061.

MLA Handbook (7th Edition):

Msmali, Ahmed Hussein O. “The effect of incomplete mixing in biological and chemical reactors.” 2013. Web. 07 Jul 2020.

Vancouver:

Msmali AHO. The effect of incomplete mixing in biological and chemical reactors. [Internet] [Doctoral dissertation]. University of Wollongong; 2013. [cited 2020 Jul 07]. Available from: ; https://ro.uow.edu.au/theses/4061.

Council of Science Editors:

Msmali AHO. The effect of incomplete mixing in biological and chemical reactors. [Doctoral Dissertation]. University of Wollongong; 2013. Available from: ; https://ro.uow.edu.au/theses/4061


Delft University of Technology

3. Gielisse, R.A.M. (author). Dynamic Local Grid Refinement for Incomplete Mixing in Reservoir Simulation.

Degree: 2015, Delft University of Technology

Reservoir simulation is a key tool to get insight in complex fluid flow phenomena occurring in many petroleum reservoirs, creating the possibility to quantify fluid productions and their uncertainty regarding many unknown properties. It has been shown by experimental and theoretical research that under certain criteria immiscible (multiphase) and miscible (single-phase) displacements can develop instabilities. These instabilities cause the displacing fluid to finger though the displaced oil, which is referred to as viscous fingering. Moreover, reservoir rock heterogeneity has shown to be capable to amply these phenomena. However, to limit computational costs, reservoir simulations typically use far lower grid resolution than the scale at which incomplete mixing phenomena occur. Numerical truncation errors imposed by large grid blocks will conceal small scale physical phenomena that contribute to unstable displacements. These sub-grid flow features are what is called incomplete mixing, as opposed to the fully mixed scenario inherent to the use of low resolution grids. To cope with this problem, effective models have been developed that make use of effective fluid properties in order to capture the sub-grid effect of incomplete mixing. Todd and Longstaff’s model is the most widely utilized model in the petroleum industry. Like similar models, one major disadvantage is that this effective model depends on an undefined scalar mixing parameter, which must be obtained from either high resolution simulation or experimental data. Dynamic local grid refinement (DLGR) is a simulation technique that can adapt the spatial grid resolution to the scale at which the physical phenomena occur without refining the grid over the entire domain. This can be achieved by means of local refinement and coarsening of the computational grid dynamically at every time step where small scale, local phenomena occur using predefined error criteria. This way DLGR could provide the means to solve for complex flow phenomena arising from instabilities at fluid fronts, while preserving complex geological features that could amplify this phenomena. This report investigates the use of state-of-the-art DLGR as an alternative to the effective model developed by Todd and Longstaff (TL). As DLGR is capable of adapting the spatial grid resolution locally where physical phenomena of incomplete mixing occur, this technique potentially allows for computational efficient and accurate results. The first part of this report studies and compares the results obtained using DLGR with that of the TL model and reference fine scale simulations for miscible transport in homogeneous media. Elaboration on DLGR's efficiency in term of CPU time, accuracy and consistency regarding scalability in terms of reservoir domain size and mobility ratio of the displaced and displacing fluid. Also a comparison is made for a secondary polymer flooding. The second part of this report investigates the accuracy of DLGR for miscible flow in heterogeneous reservoirs, and comparing the… Advisors/Committee Members: Hajibeygi, H. (mentor).

Subjects/Keywords: dlgr; incomplete mixing; instable flow; reservoir simulation; lgr; miscible; heterogeneous; homogeneous

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APA (6th Edition):

Gielisse, R. A. M. (. (2015). Dynamic Local Grid Refinement for Incomplete Mixing in Reservoir Simulation. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:be183b49-275e-4747-be20-f937a3c24f78

Chicago Manual of Style (16th Edition):

Gielisse, R A M (author). “Dynamic Local Grid Refinement for Incomplete Mixing in Reservoir Simulation.” 2015. Masters Thesis, Delft University of Technology. Accessed July 07, 2020. http://resolver.tudelft.nl/uuid:be183b49-275e-4747-be20-f937a3c24f78.

MLA Handbook (7th Edition):

Gielisse, R A M (author). “Dynamic Local Grid Refinement for Incomplete Mixing in Reservoir Simulation.” 2015. Web. 07 Jul 2020.

Vancouver:

Gielisse RAM(. Dynamic Local Grid Refinement for Incomplete Mixing in Reservoir Simulation. [Internet] [Masters thesis]. Delft University of Technology; 2015. [cited 2020 Jul 07]. Available from: http://resolver.tudelft.nl/uuid:be183b49-275e-4747-be20-f937a3c24f78.

Council of Science Editors:

Gielisse RAM(. Dynamic Local Grid Refinement for Incomplete Mixing in Reservoir Simulation. [Masters Thesis]. Delft University of Technology; 2015. Available from: http://resolver.tudelft.nl/uuid:be183b49-275e-4747-be20-f937a3c24f78

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