Lattice Boltzmann k-ω SST Based Hybrid RANS/LES Simulations of Turbulent Flows

  • Mozaffari, Sajad (M2P2)
  • Cai, Shang-Gui (M2P2)
  • Jacob, Jérôme (M2P2)
  • Sagaut, Pierre (M2P2)

Please login to view abstract download link

The lattice Boltzmann method (LBM), as a mesoscopic computational approach, has received considerable attention in recent years for high Reynolds number and moderate Mach number aerodynamic simulations, due to the linearity of its system of equations and thus low computational costs, compared to the conventional Navier-Stokes solvers. High Reynolds number simulations with LBM are computationally feasible by means of turbulence models for unresolved physical scales. Large eddy simulation (LES) is frequently used to resolve flow structures when detailed information about the flow is needed. However, LES is suffering from high computational costs especially for solving the near-wall region, where a very fine grid is needed to capture the local small flow structures. Reynolds averaged Navier–Stokes (RANS) simulation gives hope of low computational cost and reliable physics. However, to understand the detailed characteristics of turbulence, LES is still necessary. Hybrid RANS/LES models offer an excellent opportunity to save considerable computational cost, whereas preserving detailed flow information. This study focuses on the evaluation of the performance and reliability of hybrid RANS/LES models in combination with LBM for the simulation of aerodynamic external flows. The hybridization processes for these models are applied to the two-equation k-ω SST RANS model. The functionality of these hybrid models is subject to comparison through the simulation of a three-dimensional fully turbulent flow over an airfoil. In addition, they are assessed by performing a LBM simulation of an Ahmed body in order to reproduce the solution of a similar simulation with conventional CFD methods and wind tunnel experimental data. The effect of near-wall treatments on the local boundary flow structures and possible remedies are also discussed.