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Pore-scale Simulation of Flow around a Micro-porous Square Cylinder, Using Hybrid LBM-FVM, Considering Slip Condition Inside Porous Media

Rostamzadeh, Hadi | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50781 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Tayyebi Rahni, Mohammad
  7. Abstract:
  8. In recent years, application of porous media is highlighted among researchers due to their wider use in micro-scale problems, such as in gas reservoirs, micro-filtering, and heat exchangers. In such applications, accurate description of flow behavior, using governing equations based on continuum assumption, is not valid, since mean free path has the same order as the characteristic length of the problem. In such cases, imposing appropriate slip condition on the fluid-solid interface of porous media (in pore-scale level), based on kinetics theory, is an appropriate approach. For this purpose, pore-scale simulation of flow inside porous media in slippery and transient regimes is carried out here, using lattice Boltzmann method (LBM). To know how fluid interacts with porous media in such flow regimes, two different problems have been proposed and investigated. In the first problem, simulation of a rarified gas flow inside Sierpinski carpets at different porosities is carried out. The flow inside porous media is analyzed, using pore-scale simulation, using LBM. The effects of different key parameters, such as porosity and Knudsen number, on flow structure have been investigated. Also, the correlation between permeability with porosity and Knudsen number in Darcy flow regime ( ) has been presented. The results indicated that permeability varies lograithmatically and exponentially with Knudsen number and porosity, respectively. In the second problem, flow interaction inside a staggered porous media inside a channel is investigated, considering slip boundary condition inside porous media. This problem is a multi-scale problem, since the differences between time and length scales of flow inside and outside porous media are considerable. Therefore, hybrid finite volume method/lattice Boltzmann method (FVM-LBM) is used to simulate the flow behavior inside (using LBM) and outside porous media (using FVM) at different porosities and Knudsen numbers. Finally, the effect of Knudsen number on flow structures, aerodynamic coefficients, and Strouhal number at different porosities is investigated. Our results show that increasing Knudsen number inside porous media decreases drag coefficient, while increasing the amplitude of oscillatory lift coefficient
  9. Keywords:
  10. Porous Media ; Slip Boundary Condition ; Fractal Geometry ; Finite Volume Method-Lattice Boltzmann Method ; Multiscale Finite Element Method ; Pore-Scale Model ; Pore Scale Simulation of Fluid Flow

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