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You searched for subject:(Suspension balance model). Showing records 1 – 2 of 2 total matches.

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Texas A&M University

1. Xu, Feng. Interfacial Instabilities of Suspensions in Hele-Shaw Cell.

Degree: PhD, Mechanical Engineering, 2017, Texas A&M University

The objective of this research is to investigate the interfacial instability of suspensions in a Hele-Shaw cell, which involves a dynamical coupling between particle transport and fluid-fluid interfacial deformations. Interfacial instabilities have remained an important subject of research given their complicated nature. They are commonplace in multiphase flows such as enhanced oil recovery, lung airways and micro-fluidic droplets, and controlling them is of critical importance. The inclusion of particles in fluid flows can also modify the interfacial dynamics, which yet remains not well understood. The Saffman-Taylor fingering instability occurs when a less viscous fluid displaces a more viscous one in porous media, which has been extensively studied for decades. The interface is supposed to be stable in the reverse scenario, in which the more viscous fluid invades the less viscous one. Surprisingly, the inclusion of particles can fundamentally change the interfacial dynamics and even lead to interfacial instability in the absence of the unstable fluid viscosity ratio. This instability phenomenon was first reported by Tang et al and extended to squeezing suspension flows by Ramachandran. However, the research on this topic has remained qualitative. In this research, we carry out rigorous experiments to characterize the fingering instability introduced particles, by varying the particle volume fraction and the gap thickness over particle diameter ratio h=D. The experimental data are analyzed utilizing advanced image processing techniques to aid our understanding of the phenomenon. Theoretically, we use the suspension balance model to validate the shear-induced migration upstream of the expanding interface and successfully explain the mechanism behind fingering. The project is then extended to bi-disperse suspensions. The experiments are conducted with particles having different diameters by varying both the bulk particle concentration and the respective concentration of each particle species. We observe similar fingering patterns and find that the addition of small amount of large particles leads to an earlier onset of fingering. The suspension balance model is modified to accommodate the bi-disperse suspension system and then utilized to quantitatively explore the dynamics. Advisors/Committee Members: Lee, Sungyon (advisor), Petersen, Eric (committee member), Palazzolo, Alan (committee member), Daripa, Prabir (committee member).

Subjects/Keywords: interfacial instability; particle suspension migration; suspension balance model

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APA (6th Edition):

Xu, F. (2017). Interfacial Instabilities of Suspensions in Hele-Shaw Cell. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/173217

Chicago Manual of Style (16th Edition):

Xu, Feng. “Interfacial Instabilities of Suspensions in Hele-Shaw Cell.” 2017. Doctoral Dissertation, Texas A&M University. Accessed April 13, 2021. http://hdl.handle.net/1969.1/173217.

MLA Handbook (7th Edition):

Xu, Feng. “Interfacial Instabilities of Suspensions in Hele-Shaw Cell.” 2017. Web. 13 Apr 2021.

Vancouver:

Xu F. Interfacial Instabilities of Suspensions in Hele-Shaw Cell. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1969.1/173217.

Council of Science Editors:

Xu F. Interfacial Instabilities of Suspensions in Hele-Shaw Cell. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/173217


Georgia Tech

2. Miller, Ryan Michael. Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.

Degree: PhD, Chemical Engineering, 2004, Georgia Tech

A suspension flow model based on the "suspension balance" approach has been developed. This work modifies the model to allow the solution of suspension flows under general flow conditions. This requires the development of a frame-invariant constitutive model for the particle stress which can take into account the spatially-varying local kinematic conditions. The mass and momentum balances for the bulk suspension and particle phase are solved numerically using a finite volume method. The particle stress is based upon the computed rate of strain and the local kinematic conditions. A nonlocal stress contribution corrects the continuum approximation of the particle phase for finite particle size effects. Local kinematic conditions are accounted through the local ratio of rotation to extension in the flow field. The coordinates for the stress definition are the local principal axes of the rate of strain field. The developed model is applied to a range of problems. (i) Axially-developing conduit flows are computed using both the full two-dimensional solution and the more computationally efficient "marching" method. The model predictions are compared to experimental results for cross-stream particle concentration profiles and axial development lengths. (ii) Model predictions are compared to experiments for wide-gap circular Couette flow of a concentrated suspension in a shear-thinning liquid. With minor modification, the suspension flow model predicts the major trends and results observed in this flow. (iii) Comparisons are made to experiments for an axisymmetric contraction-expansion. Model predictions for a two-dimensional planar contraction flow test the influence of model formulation. The variation of the magnitude of an isotropic particle normal stress with local kinematic conditions and anisotropy in the in-plane normal stresses are both explored. The formulation of the particle phase stress is found to have significant effects on the solid fraction and velocity. (iv) Finally, for a rectangular piston-driven flow and an obstructed channel flow, a "computational suspension dynamics" study explores the effect of particle migration on the bulk flow field, system pressure drop and particle phase composition. Advisors/Committee Members: Forney, Larry (Committee Co-Chair), Morris, Jeffrey F. (Committee Co-Chair), Carr, Wallace W. (Committee Member), Koros, William J. (Committee Member), Wick, Timothy M. (Committee Member), Yiacoumi, Sotira Z. (Committee Member), Yoda, Minami (Committee Member).

Subjects/Keywords: Two-phase flow; Suspension flow; Frame-invariant rheology; Finite volume method; Shear-induced migration; Suspension balance model; Shear flow; Finite volume method; Two-phase flow; Rheology; Continuum mechanics

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

APA (6th Edition):

Miller, R. M. (2004). Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/4864

Chicago Manual of Style (16th Edition):

Miller, Ryan Michael. “Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.” 2004. Doctoral Dissertation, Georgia Tech. Accessed April 13, 2021. http://hdl.handle.net/1853/4864.

MLA Handbook (7th Edition):

Miller, Ryan Michael. “Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows.” 2004. Web. 13 Apr 2021.

Vancouver:

Miller RM. Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. [Internet] [Doctoral dissertation]. Georgia Tech; 2004. [cited 2021 Apr 13]. Available from: http://hdl.handle.net/1853/4864.

Council of Science Editors:

Miller RM. Continuum Modeling of Liquid-Solid Suspensions for Nonviscometric Flows. [Doctoral Dissertation]. Georgia Tech; 2004. Available from: http://hdl.handle.net/1853/4864

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