On the role of surface grooves in the reduction of pressure losses in heated channels

Pressure-gradient-driven flows in grooved horizontal channels were investigated. The results show that a significant reduction in pressure losses can be achieved by exposing such channels to spatially distributed heating. The system response strongly depends on the characterization of both patterns and on their relative position, leading to a pattern interaction problem. Mismatch and misplacement of both patterns may result in a significant increase in pressure losses or may have no effect on such losses. The reduction in pressure loss is associated with the formation of convection rolls on the bounding surfaces due to spatially distributed buoyancy along the streamwise direction. The pressure-gradient-reducing effect is active only in small Reynolds number flows. Explicit results are given for fluids with the Prandtl number Pr = 0.71, representing air.