Description of a 3D vortical flow by a Lattice Boltzmann method

The Lattice Boltzmann Method (LBM) has been introduced about 20 years ago, but only the recent development of a multiple-relaxation-time (MRT) collision model [1] has allowed its application to a wide range of Reynolds numbers. The comparison of its results with those obtained with a DNS incompressible- ow spectral element solver has also shown that it can correctly capture the details of the uid turbulence [2], preserving its basic features of simplicity, exibility and intrinsic parallelism. Here, we present the application of the MRT Lattice Boltzman model to a variety of uid-body interaction dealing with vorticity generation and dissipation. The vorticity is either generated in 2D or 3D lid driven cavity. The computed ow features are widely compared with data available in literature. In particular, the velocity, vorticity and pressure evolution are analyzed versus the same quantities obtained with Navier-Stokes solutions or in the experiments. The results show convergence and accuracy of the LBM solver. Finally, the 3D problem of a vortex ring impacting on a at wall is analyzed. The eects of the interaction with the solid boundary are highlighted: dissipation at low Reynolds (Re) numbers, instabilities at high Re.