横向粗糙元壁面槽道湍流的大涡模拟研究

采用大涡模拟和浸没边界法相结合对不同高度和不同间距横向粗糙元壁面槽道湍流进行了模拟,得到了光滑壁面和粗糙壁面湍流的流向平均速度分布,雷诺剪切应力,脉动速度均方根和近壁区拟序结构。结果发现横向粗糙元降低了流向平均速度,增大了流动阻力,粗糙壁面湍流的雷诺剪切应力大于光滑壁面。粗糙元降低了流向脉动速度,增强了展向和法向脉动速度。粗糙元高度越高,对湍流流动影响越大,而粗糙元间距对湍流统计特性的影响不大。粗糙壁面仍然存在着和光滑壁面类似的条带结构。

Large Eddy Simulation of Turbulent Channel Flow Over Transverse Roughness Elements

Turbulent channel flows over transverse roughness elements with different heights and intervals are investigated by large eddy simulation and immersed boundary method.Mean streamwise velocities,Reynolds shear stress,fluctuating velocities,and coherent structures near wall are obtained both for rough wall and smooth wall turbulence.The mean streamwise velocities are decreased by transverse roughness elements,and the flow drag is increased.The Reynolds shear stress of rough wall is larger than that of smooth wall.The components of fluctuating velocities in the spanwise and wall normal directions increase,while the component of fluctuating velocity in the streamwise direction decreases by roughness elements.The influence degree of roughness elements on turbulent flow statistical properties is stronger for higher roughness heights but not sensitive with roughness intervals. Streaky structures still present for rough wall turbulence that is similar with smooth wall case.