Heat transfer enhancement in a transitional channel flow

Flow modification by an array of spanwise eddy-promoters oriented normal to the flow direction is sometimes used to enhance the convective heat transfer rate from a heated wall. Here, we study the effect of such eddy-promoters on the heat transfer and dissipation in a fully-developed channel flow with one heated wall, in the laminar and transitional flow regimes. The experiment shows that flows with eddy-promoters result in a significant decrease in dissipation for a given heat transfer rate at all supercritical Reynolds numbers investigated. When the results are compared to other eddy-promoter geometries, they support a scale-matched destabilization method. The primary enhancement mechanism in the subcritical flows is travelling waves, but for supercritical flows vortex shedding is an equally important mechanism.