Affiliations: Department of Mechanical Engineering, Kyoto
University, Kyoto 606-8501, Japan.
Abstract: Vortical structures behind a wing-type vortex generator (WVG)
immersed in a drag-reducing flow were visualized with a fluorescence dye
illuminated with a planer laser sheet to investigate the enhancement mechanism
of heat transfer on the WVG-installed target wall. Particle image velocimetry
(PIV) system was also used to measure the flow velocity profiles. Both the flow
visualization and the velocity measurement revealed that small amounts of
surfactant, Cetyl-Trimethyl-Ammonium-Chloride/ Sodium Salicylate (CTAC/NaSal),
added in water changed drastically the flow patterns together with the wall
heat transfer distributions due to the reduction of momentum exchange in the
vortical flows behind WVG.