Two-point statistics of coherent structures in turbulent flow over riblet-mounted surfaces

作     者：Weipeng Li Hong Liu 

作者机构：School of Aeronautics and AstronauticsShanghai Jiao Tong UniversityShanghai 200240China 

出 版 物：《Acta Mechanica Sinica》 (力学学报（英文版）)

年 卷 期：2019年第35卷第3期

页      面：457-471页

核心收录：

学科分类：08[工学] 0801[工学-力学（可授工学、理学学位）] 

基　　金：the National Basic Research Program of China (973 program)(Grants 2014CB744802 and 2014CB744804) the National Natural Science Foundation of China (Grants 11772194 and 91441205) 

主　　题：Turbulent drag reduction Riblets Coherent structures 

摘      要：Direct numerical simulations (DNS) of turbulent flow over a drag-reducing and a drag-increasing riblet configuration are performed. Three-dimensional two-point statistics are presented for the first time to quantify the interaction of the riblet surfaces with the coherent, energy-bearing eddy structures in the near-wall region. Results provide statistical evidence that the averaged organization of the streamwise vortices in the drag-reducing case is lifted above the riblet tip, while in the drag-increasing case the streamwise vortices are embedded further into the riblet cove. In the spanwise direction, the cores of the streamwise vortices over the riblet surfaces are shown to be closer to each other than those for flow over the smooth wall, and wider riblet spacing leads to more reduction on their spanwise distances. In the cases with riblets the streamwise vortices have longer streamwise lengths, but their inclination angles do not change much.