Effect of Blockage Factor on Thermal-Fluid Flow Transport Phenomenon Over Slot-Perforated Flat Surface in Channel

A numerical and experimental study is performed to investigate unsteady, two-dimensional, incompressible laminar flow over both sides of a slot-perforated flat surface, which is placed in a channel. Enhances is placed on the effect of the blockage factor, i.e., the ratio of plate thickness, δ, to channel width, W, on the heat transfer performance and the velocity and thermal fields. It is found from the study that: (i) when the slot width is increased, the alternating change in the fluid flow disturbs the thermal boundary layer formed along the plate and induces mixing of the upper and lower streams of the plate downstream from the slot, resulting in an amplification of heat transfer performance; (ii) heat transfer performance at the rear plate is induced with an increase in d/δ and Re; and (iii) by contrast, heat transfer performance is attenuated with an increase in the blockage factor, whose effect becomes larger in the lower region of the Reynolds number. These results are confirmed by the flow visualization using ion-exchange resins.