DIRECT NUMERICAL SIMULATIONS OF FLUID-STRUCTURE INTERACTION IN THE RESPIRATORY AIRWAYS Open Access
- Other title
fictitious domain method
- Type of item
- Degree grantor
University of Alberta
- Author or creator
- Supervisor and department
Minev, Peter (Mathematical and Statistical Sciences)
Finlay, Warren (Mechanical Engineering)
- Examining committee member and department
Wong, Yaushu (Mathematical and Statistical Sciences)
Mofrad, Mohammad (Mechanical Engineering, University of California at Berkeley)
Secanell, Marc (Mechanical Engineering)
Han, Bin (Mathematical and Statistical Sciences)
Department of Mechanical Engineering
Department of Mathematical and Statistical Sciences
- Date accepted
- Graduation date
Doctor of Philosophy
- Degree level
This thesis presents recent developments in direct numerical simulations of fluid-structure interaction occurring in biological systems, with particular interest in the modeling of particle deposition within the human respiratory system.
Two numerical techniques are proposed. The first one is intended for direct numerical simulations of solid high aspect ratio micro-fibers in a general Newtonian fluid flow. For efficient and accurate resolution of the microscales, a micro-grid rigidly attached to the fiber in its spatial motion is introduced. The entire problem on the micro-grid is transformed with an Arbitrary Lagrangian-Eulerian method to a fixed reference domain and then solved with a Fictitious Domain Method. Using this algorithm, rotational behavior of fibers in a linear shear flow is studied. In view of our analysis, it is suggested that respiratory tract deposition for high aspect ratio fibers with complex shapes will be enhanced compared with the deposition of simple ellipsoidal fibers. Additionally, study of deposition enhancement due to magnetic field alignment of long straight ellipsoids in realistic airway bifurcation is performed. Results indicate that magnetic alignment of such particles can increase deep lung deposition by a factor of 1.42--3.46 depending on the fiber aspect ratio.
A second method is developed to allow direct numerical simulations of dynamical interaction between an incompressible fluid and a hyper-elastic incompressible solid.
A Fictitious Domain Method is applied so that the fluid is extended inside the deformable solid volume and the velocity field in the entire computational domain is resolved in an Eulerian framework.
Solid motion, which is tracked in a Lagrangian framework, is imposed through the body force acting on the fluid within the solid boundaries.
Solid stress smoothing on the Lagrangian mesh is performed with a Zienkiewicz-Zhu patch recovery method. High-order Gaussian integration quadratures over cut elements are used in order to avoid sub-meshing within elements in the Eulerian mesh that are intersected by the Lagrangian grid.
The method is validated against previously reported results on numerical simulations of 3-D rhythmically contracting alveolated ducts. Observed flow patterns and alveolus dynamics for breathing conditions and geometrical parameters corresponding to different acinar generations in the respiratory system are comparable to those reported previously. This suggests that our new formulation can be successfully applied to numerical studies of coupled dynamics of air and airway walls in distal regions of the lungs.
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
- Citation for previous publication
A. Roshchenko, W. H. Finlay, and P. D. Minev. The Aerodynamic Behavior of Fibers in a Linear Shear Flow. Aerosol Science and Technology, 45(10):1260--1271, Oct. 2011.R. C. Martinez, A. Roshchenko, P. D. Minev, and W. H. Finlay. Simulation of enhanced deposition due to magnetic field alignment of ellipsoidal particles in a lung bifurcation. Journal of Aerosol Medicine and Pulmonary Drug Delivery, 26(1):31--40, Feb. 2013.
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