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Simulation of Compressible Rarefied Gas Flow using High-Order WENO Finite-difference Lattice Boltzmann Method

Zamani Ashtiani, Shaghayegh | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50333 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Hejranfar, Kazem
  7. Abstract:
  8. The goal of the present study is to simulate the compressible rarefied gas flow by using a high-order finite-difference lattice Boltzmann method. Here, a weighted essentially non-oscillatory lattice Boltzmann method (WENO-LBM) is applied for the solution of the compressible form of the LB equation with the Kataoka-Tsutahara model. The solution procedure is based on the discretization of the convection terms of the LB equation using the fifth-order finite-difference WENO scheme and the temporal term using the third-order explicit total variation diminishing Runge-Kutta scheme for both the continuum and rarefied gas flows. The treatment of implementing the no-slip and slip boundary conditions is also described. The LB equation is also transformed into the generalized curvilinear coordinates and the resulting equation is solved by the WENO scheme for the continuum gas flow over the geometries with non-uniform grids and curved boundaries. The advantage of the WENO-LBM applied is that lower number of grid points are required compared to the traditional finite-difference LBMs and the solution method used is stable for the flow field with shocks and discontinuities. To fulfill the purpose of this study, at first, the simulation of the continuum gas flow is carried out and then, the solution method is extended to simulate the rarefied gas flow. The accuracy and performance of the solution procedure based on the WENO-LBM are examined by simulating different problems like the isentropic vortex, the shock tube, and the Couette flow as the continuum gas flows, and the microchannel and the micro-shock tube for different Knudsen numbers as the rarefied gas flows. The results obtained by the WENO-LBM are compared with the available numerical and direct simulation Monte Carlo (DSMC) results and it is indicated that the solution method adopted is accurate in the continuum and slip flow regimes
  9. Keywords:
  10. Lattice Boltzman Method ; Microchannel ; Rarefied Gas ; Slip Flow ; Weighted Essentially Non-Oscillatory Schemes ; Compressible Rarfied Gas Flow

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