LES analysis of unsteady characteristics of conical vortex on a flat roof

This paper discusses the unsteady characteristics of the conical vortex on a flat roof on the basis of numerical results by large eddy simulation (LES) when flow attacks oblique to the roof. There have been a number of researches regarding the pressure characteristics associated with the motion of the conical vortices. These kind of studies have been performed by wind tunnel experiments for many years. On the other hand, recent advancement of Computational Fluid Dynamic (CFD) has made it possible to easily simulate the flow characteristics around a building. So, it has been expected that CFD become a powerful tool to investigate the pressure characteristics of a building associated with the flow structure. However, the applicability of CFD to the flow around a flat roof has not reached complete understanding. First, the present LES model is validated for the prediction of the pressure characteristics on a roof for oblique flow-through comparison with the previous experimental data. Next, the unsteady motions of the conical vortex are investigated by use of a flow visualization technique.