Effects of windbreak width in wind direction on wind velocity reduction

Abstract

The variations of drag force acting on the windbreak and the bulk drag coefficients for different windbreak widths were studied experimentally in the Eiffel-type non-circulating wind tunnel at the Hydraulic Engineering Laboratory, Saitama University, Japan, to elucidate the effects of windbreak width in the wind direction on wind velocity reduction behind a windbreak. The variations of flow field for different windbreak widths were studied numerically by using the two-dimensional Reynolds-averaged Navier-Stokes (RANS) equation with a k-ε turbulence closure model. Results show that the total drag force to wind increased with increasing windbreak width, but the bulk drag coefficient decreased slightly. The relationship between the bulk drag coefficient C _d and the windbreak width W and height H can be presented by the equation of C _d=k _d (W/H)^−b (k _d, b: constants). The result of the numerical simulation shows that the windbreak width greatly affects the location and the value of the minimum wind velocity. The wind velocity decreased by 15%–22% as the windbreak width increased.

Keywords

drag force / drag coefficient / k-ε model / numerical simulation / optical porosity

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