Lattice Boltzmann Method for Forced Square-Cylinder Oscillation Problems
Date Issued
2008
Date
2008
Author(s)
Huang, Shu-Yu
Abstract
In fluid dynamics, numerical approaches are one of the powerful methods to analyze fluid fields. When traditional numerical methods are used to simulate a flow field, the first step is to divide the flow field into many discrete grids. The discrete Navier-Stokes equation of each grid is next computed. If there exists moving boundaries in the fluid field, these grids need to be re-computed or transformed in each time step. Thus, the traditional computational fluid dynamics (CFD) methods such as finite volume method (FVM) are computationally intensive, if there are moving boundaries in the fluid field. Therefore, the abatement of the computational complexities in numerical methods for processing the moving boundaries in fluid fields is the major issue of present study. In this thesis, a new numerical method, the Lattice Boltzmann Method (LBM), is introduced. LBM is combined with a numerical technique for solving the moving boundary given by Lallemand and Luo (2003), who proposed a simple bounceback scheme and a quadratic interpolation method. LBM does not need to perform the same re-computed or transformed works used in the traditional CFD, thus the performance of LBM is much better than the traditional CFD methods. Firstly, we use LBM to simulate the 2-D Couette flow and compare the efficiency and accuracy with each other. The results of the simulations show that the efficiency of LBM is better than FVM and the accuracy remains the same as FVM. We also use LBM to simulate a channel flow over a forced oscillating obstacle. In this simulation, we analyze the wake areas of the forced obstacle in several oscillating frequencies. These results are compared with the experiment of the particle image velocimetry conducted by Dutta et al. (2007). The numerical results are found to be in good agreement with the experimental data. Thus, it is concluded that LBM is efficient in processing moving boundary flow problems.
Subjects
Lattice Boltzmann method
Computational fluid dynamic
Moving boundary
Square-Cylinder oscillation
Vortex shedding frequency
Type
thesis
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