Entropic lattice Boltzmann simulation of thermal convective turbulence

We present a comprehensive study of thermal convective turbulence using a two-population entropic multi-relaxation lattice Boltzmann model. Both the canonical non-rotating and rotating Rayleigh–Bénard problems are addressed by the lattice Boltzmann simulation in the turbulent regime, ranging from high Rayleigh numbers convection in the former to geostrophic turbulence in the latter. Special attention is payed to evaluating the lattice Boltzmann method as an alternative for coarse-grid simulation in the rapidly rotating Rayleigh–Bénard regime. Results obtained for the Nusselt number scaling and flow structure are compared to direct numerical simulation and predictions of the reduced non-hydrostatic quasi-geostrophic equations. It is found that, even under a severe under-resolution of Ekman layer, the present lattice Boltzmann model is capable of capturing various regimes of thermal convective turbulence in a quantitative fashion. This study demonstrates that lattice Boltzmann method can serve an alternative to conventional turbulence modeling approaches.