Date:

2025-04-30

Title of Paper:

Experimental study of drag-reduction mechanism for a dilute surfactant solution flow

Journal:

Int J Heat Mass Transfer

Summary:

The quantitative characteristics of vortex structures and turbulent events in turbulent channel flows with and without drag reduction were investigated experimentally. Drag reducing aqueous solutions of CTAC (CTAC – cetyltrimethyl ammonium chloride) with concentration of 25 ppm and 75 ppm at 30 C were tested. Particle image velocimetry (PIV) was used to measure the instantaneous velocity field in the streamwise–wall- normal plane of the flow. Through visualizing the instantaneous vector fields, contour maps of the swirling strength and instantaneous value of uv (u and v are the streamwise and wall-normal velocity fluctuations, respectively), the characteristic angle of vortex packets was quantified. It was shown that the drag-reducing CTAC additive reduced both the strength and frequency of turbulent bursts near the wall, and the characteristics of vortex structures and bursts were not only dependent on drag-reduction level but also on concentration of additive. From the quantified parameters characterizing turbulent events in a wall-bounded turbulent flow, it was obtained that fT was linearly proportional to the product of frequency and strength of turbulent events.

Co-author:

F. C. Li, Y. Kawaguchi, B. Yu, J. J. Wei

Volume:

51(3-4)

Page Number:

835-843

Translation or Not:

No

Date of Publication:

2008-09-17