有孔フェンス周囲の非定常流れ場の数値シミュレーション

Abstract

Porous fence is an effective device to control the wind flow and to reduce the wind force. The aerodynamic characteristics those necessary to wind resistant design are usually examined by experiment because of the variety of materials and the difficulty of simulating the flow in and around the porous objects. Here we present a practical method for numerical prediction of unsteady flow around a fence. Reproduction of the configuration of solid obstacles in the fine mesh discretization is a direct way to make numerical calculations on porous objects. However, calculations using the fine mesh increase the computational load and can cost a lot of time and money. In order to reduce these factors, we applied space averaging to the Navier-Stokes equations and derived filtered equations with a subgrid scale turbulent modelling for the Large Eddy Simulation. We adopt the turbulent modeling to a porous fence and calculate the space-averaged property of flows with coarse meshes without a heavy computational load. The model drag coefficient was examined by a calculation with fine mesh and by an optimization with coarse mesh. Finally, we also present a calculated turbulent field around a porous fence placed on a flat plane and compare the result to a wind tunnel test. Simulated flows showed good agreement with experimental data.