Direct numerical simulations of turbulent boundary layers with roughness elements on a wall were performed to investigate the spatial characteristics of rough-wall turbulence and establish a corresponding prediction method. When the roughness height was larger than the buffer layer, the rough-wall turbulence exhibited different spatial characteristics of the turbulence structures from those pertaining to a smooth wall. A novel spatial scaling method was established to examine the universal spatial characteristics of turbulence structures in the presence and absence of wall roughness. Specifically, the viscous length was determined by modifying the definition of the friction velocity in the region in which the roughness influenced the flow. The rough-wall turbulence could be accurately predicted by performing large eddy simulations using the subgrid scale model with the filter width, which was modified using the proposed spatial scaling method. The proposed model can be used to design more efficient fluid machinery in engineering applications.

通过对壁面粗糙元素湍流边界层的直接数值模拟，研究粗糙壁面湍流的空间特征并建立相应的预测方法。当粗糙高度大于缓冲层时，粗糙壁湍流表现出不同于光滑壁湍流结构的空间特征。建立了一种新的空间缩放方法来检查存在和不存在壁面粗糙度的湍流结构的普遍空间特征。具体而言，粘性长度是通过修改粗糙度影响流动的区域中摩擦速度的定义来确定的。粗糙壁湍流可以通过使用具有滤波器宽度的子网格尺度模型执行大涡模拟来准确预测，该模型使用所提出的空间尺度方法进行了修改。所提出的模型可用于在工程应用中设计更高效的流体机械。