Effects of surfactant on free-surface turbulent shear flow
Journal
International Communications in Heat and Mass Transfer
Journal Volume
23
Journal Issue
8
Pages
1087-1095
Date Issued
1996
Author(s)
Tsai, W.-T.
Abstract
We study the effects of surfactant (surface active material) on the turbulent shear layer near the free surface by analyzing the data from direct numerical simulation of the flow. It is found that the blocking effect of a clean surface (attenuation of the vertical fluctuating velocities and increase in the horizontal turbulence intensity) is significantly changed by the surfactant contamination. Within a viscous sublayer next to the contaminated surface, both horizontal and vertical turbulent intensities are attenuated approaching the surface. In addition, coherent vortex-connection signatures, which are found on a clean surface, are diminished with the presence of surfactant. The differences between the effects of clean and contaminated surfaces on the surface features and the underlying turbulence are explained by the coupling interaction between the surfactant transport and the underlying coherent horseshoe vortices. Copyright © 1996 Elsevier Science Ltd.
Type
journal article