非線形k-εモデルによる開水路流れにおける大規模渦運動の三次元解析

概要

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The flow behaviour around a square cylinder is characterized by the unsteady 3-D structures induced by the Karman vortex and the horseshoe vortex formations. The plane 2-D and the 3-D numerical models are applied to the computations of those flows in both the closed and open water channels. In the plane 2-D calculation, the depth-averaged shallow water flow equations, which have been used for various problems in river engineering works, are applied to the flow in open channels. For the sake of simplicity, the eddy viscosity coefficient is evaluated by the simplified 0-equational formulation. The non-linear k-ε model which includes the effect of the strain parameter is used in the 3-D computations of the flows in closed and open channels. Applicability of the turbulence model to the Karman vortex shedding in the 2-D flow field is firstly investigated through the comparison of the calculated results with the experimental ones conducted in the closed water section by Lyn and the model constants are adjusted. Then, the 3-D computations of unsteady flows in open channels are carried out focusing on the Karman vortex and the horseshoe vortex generated around the cylinder. Effects of the depth to the 3-D flow structures in open channels are also discussed through the comparison of the numerical results under different conditions of water depth.
四日市大学の論文
1999-03-30