非定常RANSによる二次元地形上気流の数値シミュレーション

抄録

A new method of simulating turbulent flows is proposed, which works like an LES method when the grid size is small enough to resolve time-dependent large eddies and reduces to a conventional Reynolds-avenged Navier-Stokes equation method when the grid size becomes large. The transition is achieved by introducing the switch-over function applied to the eddy viscosity coefficient that is determined by a method similar to existing two-equation models. The method has been applied to flows over smooth topography with or without flow separation. The results give detailed time-accurate flow field that have not been possible by a conventional unsteady RANS techniques and the time-averaged results agree well with experimental results