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首页> 外文期刊>Bulletin of the American Physical Society >APS -70th Annual Meeting of the APS Division of Fluid Dynamics- Event - Roughness topographical effects on mean momentum and stress budgets in developed turbulent channel flows
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APS -70th Annual Meeting of the APS Division of Fluid Dynamics- Event - Roughness topographical effects on mean momentum and stress budgets in developed turbulent channel flows

机译：APS-APS流体动力学分部第70届年会-事件-崎top地形对发达湍流通道中平均动量和应力预算的影响

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Direct numerical simulations of turbulent channel flows are carried out over two surfaces: a synthesized sand-grain surface and a realistic turbine roughness that is characterized by more prominent large-scale surface features. To separate the effects of wall-normal variation of the roughness area fraction from the (true) variation of flow statistics, the governing equations are area-averaged using intrinsic averaging, contrary to the usually practice based on the total area (i.e., superficial averaging). Additional terms appear in the mean-momentum equation resulted from the wall-normal variation of the solid fraction and play a role in the near-wall balance. Results from surfaces with a step solidity function (e.g., cubes) will also be discussed.Compared to the sand grains, the turbine surface generates stronger form-induced fluctuations, despite weaker dispersive shear stress. This is associated with more significant form-induced productions (comparable to shear production) in Reynoldsstress budgets, weaker pressure work, and, consequently, more anisotropic redistribution of turbulent kinetic energy in the roughness sublayer, which potentially leads to different turbulent responses between the two surfaces in non-equilibrium flows.
机译：湍流通道流动的直接数值模拟是在两个表面上进行的：合成的沙粒表面和实际的涡轮粗糙度，其特征在于更突出的大规模表面特征。为了将粗糙度区域分数的壁法线变化与流量统计的（真实）变化区分开来，使用内在平均对控制方程进行面积平均，这与通常基于总面积的做法相反（即，表面平均） ）。附加项出现在由固相的壁法线变化产生的平均动量方程中，并在近壁平衡中起作用。具有阶跃稳固性函数的表面（例如立方体）的结果也将被讨论，与沙粒相比，尽管分散剪切应力较弱，但涡轮机表面仍会产生更强的形状引起的波动。这与雷诺应力预算中形式产生的产量更高（可与剪切产生的产量相比），压力功较弱以及因此在粗糙度子层中湍动能的各向异性重新分布有关，这有可能导致两者之间的湍流响应不同非平衡流动中的表面。

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