Abstract: Mesh division is an important part of fire numerical simulation, which has a great influence on the accuracy of simulation results and simulation time. Aiming at mesh division in fire numerical simulation, a mesh optimization method based on Large Eddy Simulation (LES) is proposed. According to the principle of decomposing motion signals in LES, a calculation method of filter scale is proposed, and the grid sizes of different areas in the fire field are optimized and adjusted according to filter scale and grid ratio coefficient. The optimization method is applied to a high-rise building fire simulation, and FDS software is used to carry out numerical simulations on the pre-optimization mesh, post-optimization mesh and fine mesh respectively. Temperature, oxygen and carbon dioxide volume fractions of different mesh division are compared. The results show that: after mesh optimization, the mean value of the correlation coefficient with the fine grid simulation results is 0.987, which ensures the simulation accuracy. At the same time, the simulation running time is reduced to 16% of the fine grid, which effectively improves the computational efficiency of fire simulation.

Key words: mesh optimization, fire simulation, large eddy simulation, high-rise building