Laser anemometer measurements of Reynolds stress in a turbulent channel flow with drag reducing polymer additives

Willmarth, W. W.; Wei, T.; Lee, C. O.
April 1987
Physics of Fluids (00319171);Apr87, Vol. 30 Issue 4, p933
Academic Journal
Turbulence measurements with a high resolution laser Doppler anemometer in a channel flow with injection of a concentrated polyethylene oxide solution are reported. With polymer injection sufficient to yield a well mixed concentration of 10 ppm the total drag is reduced by 38%, but the sum of the Reynolds stress and the conventional molecular shear stress is only 2/3 of the force produced by the streamwise pressure gradient. Thus, the injected polymer solution has a significant effect on the turbulence and causes an additional retarding force equal to approximately 1/3 of the total drag.


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