Hostname: page-component-cd9895bd7-gxg78 Total loading time: 0 Render date: 2024-12-20T08:41:29.615Z Has data issue: false hasContentIssue false
  • English
  • Français

Drag reduction by polymer additives in a turbulent channel flow

Published online by Cambridge University Press:  24 June 2003

TAEGEE MIN ,
JUNG YUL YOO ,
HAECHEON CHOI  and
DANIEL D. JOSEPH
TAEGEE MIN
Affiliation:
Center for Turbulence and Flow Control Research, Institute of Advanced Machinery and Design, Seoul National University, Seoul 151-742, Korea
JUNG YUL YOO
Affiliation:
School of Mechanical and Aerospace Engineering, Seoul National University Seoul 151-742, Korea
HAECHEON CHOI
Affiliation:
Center for Turbulence and Flow Control Research, Institute of Advanced Machinery and Design, Seoul National University, Seoul 151-742, Korea School of Mechanical and Aerospace Engineering, Seoul National University Seoul 151-742, Korea
DANIEL D. JOSEPH
Affiliation:
Department of Aerospace Engineering and Mechanics, University of Minnesota, 107 Akerman Hall, 110 Union Street SE, Minneapolis, MN 55455, USA
Get access Rights & Permissions [Opens in a new window]

Abstract

Turbulent drag reduction by polymer additives in a channel is investigated using direct numerical simulation. The dilute polymer solution is expressed with an Oldroyd-B model that shows a linear elastic behaviour. Simulations are carried out by changing the Weissenberg number at the Reynolds numbers of 4000 and 20 000 based on the bulk velocity and channel height. The onset criterion for drag reduction predicted in the present study shows a good agreement with previous theoretical and experimental studies. In addition, the flow statistics such as the r.m.s. velocity fluctuations are also in good agreement with previous experimental observations. The onset mechanism of drag reduction is interpreted based on elastic theory, which is one of the most plausible hypotheses suggested in the past. The transport equations for the kinetic and elastic energy are derived for the first time. It is observed that the polymer stores the elastic energy from the flow very near the wall and then releases it there when the relaxation time is short, showing no drag reduction. However, when the relaxation time is long enough, the elastic energy stored in the very near-wall region is transported to and released in the buffer and log layers, showing a significant amount of drag reduction.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 486 , 10 June 2003 , pp. 213 - 238
Copyright
© 2003 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)