Numerical Simulation of Asymmetrical Flow and Heat Transfer Behind a Hill in Shear Flows

Three-dimensional numerical simulations of asymmetrical flows and heat transfer around a hill in shear flows were performed. When shear velocity distributions are introduced at the inlet, a vortex pair is formed asymmetrically to the spanwise direction behind the hill. Further, an asymmetrical hairpin vortex is periodically generated downstream. The leg of the asymmetrical hairpin vortex on the high-speed side collapses first. Further downstream, the asymmetrical hairpin vortex breaks down earlier than the symmetrical hairpin vortex, and streamwise vortices appear on the high-speed side. These streamwise vortices increase the heat transfer downstream. In contrast, no hairpin vortex appears in the case of a strong shear velocity distribution, but instead a streamwise vortex appears. The heat transfer decreases downstream since the turbulence generated by streamwise vortices is weak. (C) 2008 Wiley Periodicals, Inc.