Abstract
Some wall stress models have been proposed to reduce the CPU time required in LES and to predict with a good accuracy. We improve the 0 equation model of the turbulent eddy viscosity in the differential equations model using the gradient Richardson number. In this model we calculated the strongly swirling flow inside the cylindrical furnace. There is no difference between the improved model and non-improved model. If the tangential mean velocities are compared between LES and the experiment, that of LES is a free-vortex-type but that of the experiment is a forced-vortex type.