Experimental investigation on drag reduction in turbulent boundary layer over superhydrophobic surface by TRPIV  

作　　者：Haiping Tian Jingxian Zhang Erdan Wang Zhaohui Yao Nan Jiang 

机构地区：[1]Department of Mechanics,Tianjin University [2]Department of Engineering Mechanics,School of Aerospace,Tsinghua University [3]Tianjin Key Laboratory of Modern Engineering Mechanics

出　　处：《Theoretical & Applied Mechanics Letters》2015年第1期45-49,共5页力学快报（英文版）

基　　金：supported by the National Natural Science Foundation of China(11272233,11272176,11411130150,and 11332006(key project));National Basic Research Program(973Program)(2012CB720101 and 2012CB720103)

摘　　要：This study aims at the mechanism of drag reduction in turbulent boundary layer （TBL） with superhy- drophobic surface. Comparing the time-resolved particle image velocimetry （TRPIV） measurement results with that of hydrophilic surface, the drag reduction rate over a superhydrophobic surface is approximately 10%. To investigate the characteristics of coherent structure in a drag-reduced TBL with superhydropho- bic surface, a modified multi-scale spatial locally-averaged structure function is proposed for detecting coherent structure. The conditional sampling and spatial phase-lock average methods are employed to obtain the topology of physical quantities like the velocity fluctuation, spanwise vorticity, and Reynolds stress during eject and sweep process. The results indicate that the suppression of coherent structure burst in the near-wall region is the key mechanism in reducing the skin friction drag for TBL over super- hydrophobic surface.This study aims at the mechanism of drag reduction in turbulent boundary layer （TBL） with superhy- drophobic surface. Comparing the time-resolved particle image velocimetry （TRPIV） measurement results with that of hydrophilic surface, the drag reduction rate over a superhydrophobic surface is approximately 10%. To investigate the characteristics of coherent structure in a drag-reduced TBL with superhydropho- bic surface, a modified multi-scale spatial locally-averaged structure function is proposed for detecting coherent structure. The conditional sampling and spatial phase-lock average methods are employed to obtain the topology of physical quantities like the velocity fluctuation, spanwise vorticity, and Reynolds stress during eject and sweep process. The results indicate that the suppression of coherent structure burst in the near-wall region is the key mechanism in reducing the skin friction drag for TBL over super- hydrophobic surface.

关 键 词：Superhydrophobic surfaceDrag reductionTBLTRPIVSpatial topology 

分 类 号：O357.5[理学—流体力学]