DOI: 10.1615/ICHMT.2009.TurbulHeatMassTransf
ISBN Print: 978-1-56700-262-1
ISSN: 2377-2816
Spatial structure in the drag reducing channel flow of viscoelastic fluid
RÉSUMÉ
A drag reducing flow with surfactant additives in the two-dimensional channel was investigated experimentally. We carried out detailed measurements of the instantaneous velocity u-w in the x-z plane by using Particle Image Velocimetry (PIV). The surfactant used in this experiment is a kind of cationic surfactant CTAC. We paid attention to the effects of Reynolds number ranging from 15000 to 25000 and weight concentration of CTAC preparing 25 and 40 ppm on the flow. As a result of this study, in the drag reducing flow, there appeared an area where the root mean square (RMS) of streamwise velocity fluctuation ω,sub>yrms and RMS of the vortex fluctuation ωyrms sharply decrease with increasing y/(H/2). Therefore, it seems that two layers having different turbulent structure coexist on the boundary of this area. These characteristic structures of drag reducing flow were can be explained by the coexistence of two layers characterized by SIS.