Heat transfer enhancement by blowing and suction in channel flow at low Reynolds number

Abstract

The heat transfer enhancement is of importance in the low Reynolds number flow, because small heat exchangers with narrow flow passages are required recently. In this study, we investigate the heat transfer enhancement effect by ordinal feedback control techniques in a channel flow by means of direct numerical simulations. As control technique, the blowing and suction are imposed based on the near-wall velocity and the control is designed to promote turbulence and enhance the heat transfer. As results, the skin-friction drag and heat transfer are sustained at the fully turbulent level when an amplitude of the blowing and suction is small. On the other hand, these are larger than that when the amplitude is comparable to the near-wall normal velocity.