A numerical model is developed to investigate the flow in porous media, for the purposes of simulating scour protection around coastal and offshore structures. In the present model, the Volume-Averaged Reynolds Averaged Navier-Stokes (VARANS) equations are solved, coupled with the volume-averaged turbulence closure. The volume-averaged equations are derived by taking the spatial average of the standard equations. The unknown coefficients caused by the averaging procedure are determined by large eddy simulation (LES). The developed model is validated against existing experimental results of flow in stone covers under both oscillatory and steady current conditions. A gradual transition of porosity towards unity at the interface between the porous media and the free flow is assumed in the simulation to fit the irregular interface in practical engineering. In the presence of parabolic porosity variation at the interface, the calculated velocity profile, bed shear stress, and turbulent fluctuations inside the porous medium are compared to measurements. The numerical results match well against the experimental data. Comparison with the volume-averaged turbulence model shows that the volume-averaged turbulence model provides more accurate flow behavior within the porous media.

中文翻译：

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使用改进的 k-ω 湍流模型对石材保护层内的流动进行数值模拟

开发了一个数值模型来研究多孔介质中的流动，以模拟沿海和近海结构周围的冲刷保护。在本模型中，求解了体积平均雷诺平均纳维-斯托克斯 (VARANS) 方程，并结合了体积平均湍流闭合。体积平均方程是通过对标准方程进行空间平均而得出的。由平均过程引起的未知系数由大涡模拟（LES）确定。所开发的模型根据振荡和稳定电流条件下石盖中流动的现有实验结果进行了验证。模拟中假设多孔介质和自由流动之间的界面处的孔隙率逐渐过渡到统一，以适应实际工程中的不规则界面。在界面处存在抛物线孔隙率变化的情况下，将计算出的速度剖面、床剪切应力和多孔介质内部的湍流波动与测量值进行比较。数值结果与实验数据吻合良好。与体积平均湍流模型的比较表明，体积平均湍流模型在多孔介质内提供了更准确的流动行为。