Influence of rheological parameters in all drag reduction regimes of turbulent channel flow with polymer additives  

作　　者：李昌烽 赵作广 吴桂芬 冯晓东 

机构地区：[1]School of Energy and Power Engineering,Jiangsu University

出　　处：《Journal of Central South University》2008年第S1期275-279,共5页中南大学学报（英文版）

基　　金：Project (10672069) supported by the National Natural Science Foundation of China

摘　　要：The influence of rheological parameters on vortex dynamics and the extent of drag reduction (DR) were deciphered via extensively analyzing the hi-fidelity direct numerical simulation results of the turbulent channel flow with polymer solutions. It has been observed that in all drag reduction regimes from the onset of DR to maximum drag reduction (MDR) limit, the Deborah number is defined as the product of an effective Weissenberg number, and the root mean square streamwise vorticity fluctuation remains O(1) in the near wall region. The ratio of the average lifetime of axial vortices to the vortex rotating duration decreases with increasing DR, and MDR is achieved when these time scales become nearly equal. Based on these observations a simple framework is proposed adequately to describe the influence of polymer additives on the extent of DR from onset to MDR as well as the universality of the MDR in flow systems with polymer additives.<Abstract>The influence of rheological parameters on vortex dynamics and the extent of drag reduction(DR) were deciphered via extensively analyzing the hi-fidelity direct numerical simulation results of the turbulent channel flow with polymer solutions.It has been observed that in all drag reduction regimes from the onset of DR to maximum drag reduction(MDR) limit,the Deborah number is defined as the product of an effective Weissenberg number,and the root mean square streamwise vorticity fluctuation remains O(1) in the near wall region.The ratio of the average lifetime of axial vortices to the vortex rotating duration decreases with increasing DR,and MDR is achieved when these time scales become nearly equal.Based on these observations a simple framework is proposed adequately to describe the influence of polymer additives on the extent of DR from onset to MDR as well as the universality of the MDR in flow systems with polymer additives.

关 键 词：drag reduction DILUTE POLYMERIC solutions TURBULENT channel flows FENE-P model 

分 类 号：O631.3[理学—高分子化学]