Simulation of the mushroom cloud generated from a high-energy explosion using large-eddy simulation

We performed numerical simulations of a 20 kT heavy explosion to predict the rise and diffusion of mushroom cloud after the atmospheric pressure is recovered around the burst point. We proposed a new formulation of governing equations based on the anelastic approximation and density weighted variables to implement the atmospheric stratification by employing potential temperature to account for the effect of atmospheric pressure variation in altitude. To validate the simulation results, we chose similar explosive yield cases performed at the Nevada sites to compare the mushroom cloud height and diameter. Parametric studies were performed by varying the grid size and global subgrid-scale coefficients, C_s, to find the appropriate value that guarantees reliability of simulation results. Based on the optimal simulation results, the cooling process of mushroom cloud and the suppressed ascending air currents around tropopause were investigated.