Implicit lattice boltzmann method for laminar/turbulent flows

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2016
Çevik, Fatih
Lattice Boltzmann Method is an alternative computational method for fluid physics problems. The development of the method started in the late 1980s and early 1990s. Various numerical schemes like stream and collide, finite difference, finite element and finite volume schemes are used to solve the discrete Lattice Boltzmann Equation. Almost all of the numerical schemes in the literature are explicit schemes to exploit the natural features of the discrete Lattice Boltzmann Equation like parallelism and easy coding. In this thesis, an Implicit Finite Volume Lattice Boltzmann Method (IFVLBM) is developed. The method is limited for the incompressible fluid simulation, however loosely coupled Spalart-Allmaras turbulence model is incorporated for the simulations for high Reynolds numbers. Moreover, local time stepping techniques and dual time stepping techniques are also implemented for convergence acceleration to use in steady state and unsteady problems respectively. The IFVLBM demonstrates improvements in stability characteristics and convergence is accelerated as the limitation of CFL number is eased compared to the classical Lattice Boltzmann Methods. The test case results for laminar, turbulent, steady and unsteady flows are compared with either experimental or numerical data in the literature. Also, numerical data available in the literature from the CFL3D software, which is a Reynolds averaged Navier Stokes solver developed by NASA, is used for flow field comparisons. The results of the developed method are in good agreement with the data given in the literature.