Abstract
The effects of a porous fence with a nonuniform porosity on flow fields are investigated numerically. First, an experiment with a non‐uniform porous fence located in a wind tunnel is performed to obtain a reference data set. Then, a numerical model that utilizes the finite volume scheme with a weakly compressible‐flow method to solve the continuity and momentum equations is developed. The numerical simulation is compared to experimental measurements for validation purposes. As a result, the numerical predictions show good agreements with the experimental data. Finally, the numerical investigations of the flow fields around porous fences with various combinations of upper and lower fence porosity are also presented. When the upper porosity is greater than the lower porosity, the Protection Index PI0.1, PI0.3 and PI0.5, representing the adverse sheltering effect, decreases compared to that of the uniform porous fence. When the upper porosity is less than the lower porosity, the PI0.5 increases and the variations of the PI0.1 and PI0.3, depend on the upper porosity, compared to that of the uniform porous fence. The results show that the porous fence with the upper fence porosity εU = 0% and the lower fence porosity εL = 30% gives the best sheltering effect among the porous fences in this study.
Highlights
Various kinds of fences have been used as windbreaks to reduce the wind erosion effectively
The results show that the porous fence with the upper fence porosity εU 0% and the lower fence porosity εL 30% gives the best sheltering effect among the porous fences in this study
The effect of nonuniform porous fence on flow fields are simulated by varying the combinations of upper and lower fence porosity
Summary
Various kinds of fences have been used as windbreaks to reduce the wind erosion effectively. A fence blocks the oncoming flow and reduces the mean velocity of the flow behind the fence. Flows around a fence are of complex characteristics. Flow separation from fences results in strong shear layers, along which turbulence intensities are large. The high turbulence level and the shear layer of the recirculation flow in the near wake region. Variations of fence porosity are to modify the flow velocity and to control the turbulence structure around the fence. In order to evaluate the sheltering effect properly and efficiently, a deeper understanding of the underlying dynamics of the turbulent structures is required
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