Development of locally mesh-refined Lattice Boltzmann Method by using Temporal Blocking Method

Onodera, Naoyuki   ; Idomura, Yasuhiro   ; Ali, Y.*

A real-time simulation of the environmental dynamics of radioactive substances is very important from the viewpoint of nuclear security. Since a lot of tall buildings and complex structures make the air flow turbulent in urban cities, large-scale CFD simulations are needed. To this end, a CFD code based on a Lattice Boltzmann Method (LBM) with a block-based Adaptive Mesh Refinement (AMR) method is developed. As the conventional LBM based on a single relaxation time collision operator often becomes numerically unstable at high Reynolds number, we apply a state-of-the-art cumulant collision operator. The code is developed on a GPU cluster at JAEA. By using new functions in CUDA8.0, the GPU kernel functions are tuned to achieve high performance on the latest Pascal GPU architecture. By introducing a temporal blocking technique, we achieve a high performance of 488 MLUPS per a GPU, and the number of the MPI communications is significantly reduced.