配管系における非圧縮性粘性流の解析

概要

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A numerical method was developed to solve three-dimensional incompressible viscous flow in complicated geometries using a domain decomposition technique. Each complicated flow domain was decomposed into several subdomains. Curvilinear coordinates were numerically generated in each subdomain using the boundary-fitted coordinate transformation technique. The method was adopted to solve some benchmark problems. For a two-dimensional cavity flow, the obtained flow velocity distributions agreed very well with the numerical results given by Ghia et al. The calculated flow velocity distributions in a 180°curved pipe were also in good agreement with the experimental ones. The method was applied to the analysis of flows with a large Reynolds number (≒10^4) in piping elements. The calculations indicated a strong secondary flow and eddy train produced at an elbow. In a diffuser, eddies were found to be produced almost symmetrically with respect to the central axis for a small expansion angle, but the flow pattern became more unsymmetric and unsteady for a larger expansion angle. The insufficient recovery of pressure in the diffuser was found to be caused by the generation of eddies.
1991-08-25