中文摘要：

采用直接数值模拟的方法，对湍流边界层内加入两个半球粗糙元的流动进行研究，探索加入粗糙元后流场的边界层厚度、速度场、涡量、压力梯度等统计量规律。发现加入粗糙元后，原来的流场结构受到了粗糙元的破坏，层流受到这种强影响而转化为湍流，边界层的厚度在波动中不断增大。半球粗糙元造成了其表面上边界层的分离，并在后方产生了对流场的作用强烈的强雷诺应力区域。

英文摘要：

This paper describes a DNS study on effect of adding two hemispheres roughness element in the turbulent boundary layer flow, which explore the boundary layer thickness, velocity field, pressure gradient and other laws of statistics. Discovered that after adding roughness elements, the original structure of the flow field are destructed, so that the laminar flow are transited into turbulence, and the boundary layer thickness in the growing process are vibrated. The hemisphere surface rough- ness elements cause the separation of boundary layer, and strong Reynolds stress regions are in its rear.