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You searched for +publisher:"Brown University" +contributor:("Caswell, Bruce"). Showing records 1 – 2 of 2 total matches.

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1. Fedosov, Dmitry A. Multiscale Modeling of Blood Flow and Soft Matter.

Degree: PhD, Applied Mathematics, 2010, Brown University

This work presents multiscale modeling of blood flow and polymer suspensions which requires the use of heterogeneous modeling approaches. A hybrid method based on coupling the Molecular Dynamics (MD) method, the Dissipative Particle Dynamics (DPD) method, and the incompressible Navier-Stokes (NS) equations is developed and is called the Triple-Decker algorithm. MD, DPD, and NS are formulated in separate subdomains and are coupled via an overlapping region by communicating state information at the subdomain boundaries. The triple-decker algorithm is verified for several prototype flows such as Couette, Poiseuille, and lid-driven cavity flow. A three-dimensional multiscale red blood cell (RBC) model is developed and is able to predict RBC mechanics, rheology, and dynamics in agreement with experiments. Based on an analytic theory, the modeled membrane properties can be uniquely related to the experimentally established RBC macroscopic properties without any adjustment of parameters. The developed model is applied to modeling infected RBCs in malaria where RBC membrane properties can dramatically change. Blood flow is simulated in microtubes for different diameters and hematocrit values. The blood flow model captures the well-known Fahraeus and Fahraeus-Lindquist effects and cell-free layers measured in experiments. Blood flow in malaria is characterized by the adhesion of infected RBCs to the vascular endothelium. The adhesive dynamics of infected RBCs in malaria is simulated based on the stochastic bond formation/dissociation model and compares well with experimental observations. Depletion layers in dilute polymer solutions in micro- and nano-channels are investigated for various conditions and compare well with the asymptotic lattice theory solution of depletion near a repulsive wall. In Poiseuille flow, polymer migration across the streamlines results in two symmetric off-center peaks in the center-of-mass distribution which identify the preferred chain positions across the channel. Steady state rheological properties of semi-dilute polymer solutions and melts are obtained with the Reverse Poiseuille flow (RPF) which is demonstrated to be an accurate and convenient virtual rheometer for complex fluids. For isothermal solutions the material functions satisfy the principle of time-concentration superposition, while for undiluted chains the temperature dependence is reconciled by the principle of time-temperature superposition. Advisors/Committee Members: Karniadakis, George (Director), Caswell, Bruce (Reader), Maxey, Martin (Reader).

Subjects/Keywords: hybrid method

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

APA (6th Edition):

Fedosov, D. A. (2010). Multiscale Modeling of Blood Flow and Soft Matter. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:11038/

Chicago Manual of Style (16th Edition):

Fedosov, Dmitry A. “Multiscale Modeling of Blood Flow and Soft Matter.” 2010. Doctoral Dissertation, Brown University. Accessed October 22, 2019. https://repository.library.brown.edu/studio/item/bdr:11038/.

MLA Handbook (7th Edition):

Fedosov, Dmitry A. “Multiscale Modeling of Blood Flow and Soft Matter.” 2010. Web. 22 Oct 2019.

Vancouver:

Fedosov DA. Multiscale Modeling of Blood Flow and Soft Matter. [Internet] [Doctoral dissertation]. Brown University; 2010. [cited 2019 Oct 22]. Available from: https://repository.library.brown.edu/studio/item/bdr:11038/.

Council of Science Editors:

Fedosov DA. Multiscale Modeling of Blood Flow and Soft Matter. [Doctoral Dissertation]. Brown University; 2010. Available from: https://repository.library.brown.edu/studio/item/bdr:11038/

2. Pan, Wenxiao. Single Particle DPD: Algorithms and Applications.

Degree: PhD, Applied Mathematics, 2010, Brown University

This work presents the new single particle dissipative particle dynamics (DPD) model for flows around bluff bodies that are represented by single DPD particles. This model leads to an accurate representation of the hydrodynamics and allows for economical exploration of the properties of complex fluids. The new DPD formulation introduces a shear drag coefficient and a corresponding term in the dissipative force that, along with a rotational force, incorporates non-central shear forces between particles and preserves both linear and angular momenta. First, we simulated several prototype Stokes flows to verify the performance of the proposed formulation. Next, we demonstrated that, in colloidal suspensions, the suspended spherical colloidal particles can effectively be modeled as single DPD particles. In particular, we investigated the rheology, microstructure and shear-induced migration of a monodisperse colloidal suspension in plane shear flows. The simulation results agree well with both experiments and simulations by the Stokesian Dynamics. Then, we developed a new low-dimensional red blood cell (LD-RBC) model based on this single particle DPD algorithm. The LD-RBC model is constructed as a closed-torus-like ring of 10 DPD particles connected by wormlike chain springs combined with bending resistance. The LD-RBC model is able to capture the linear and non-linear elastic deformations for healthy and malaria-infected cells. Also, it reproduces the key features of blood flow in vessels such as the cell free layer, the Fahraeus effect and the Fahraeus-Lindqvist effect, except for capillaries of sizes comparable to the cell diameter. The discrepancy is caused by the simplified representation of the RBC 3D structure, which becomes more critical for blood flow in small tubes. Finally, we examined the effect of aggregation of RBCs on the blood rheology. To reproduce the tendency of RBCs to form structures known as "rouleaux", a weak anisotropic attractive interaction derived from the Morse potential is included with each RBC. A reversible rouleau formation is reproduced. The presence of rouleaux causes a great increase in the low-shear-rate viscosity of the suspensions, and a non-zero yield stress. Both are consistent with experimental studies. Advisors/Committee Members: Karniadakis, George (Director), Caswell, Bruce (Reader), Maxey, Martin (Reader).

Subjects/Keywords: dissipative particle dynamics

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

APA (6th Edition):

Pan, W. (2010). Single Particle DPD: Algorithms and Applications. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:11115/

Chicago Manual of Style (16th Edition):

Pan, Wenxiao. “Single Particle DPD: Algorithms and Applications.” 2010. Doctoral Dissertation, Brown University. Accessed October 22, 2019. https://repository.library.brown.edu/studio/item/bdr:11115/.

MLA Handbook (7th Edition):

Pan, Wenxiao. “Single Particle DPD: Algorithms and Applications.” 2010. Web. 22 Oct 2019.

Vancouver:

Pan W. Single Particle DPD: Algorithms and Applications. [Internet] [Doctoral dissertation]. Brown University; 2010. [cited 2019 Oct 22]. Available from: https://repository.library.brown.edu/studio/item/bdr:11115/.

Council of Science Editors:

Pan W. Single Particle DPD: Algorithms and Applications. [Doctoral Dissertation]. Brown University; 2010. Available from: https://repository.library.brown.edu/studio/item/bdr:11115/

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