Drag Reduction and Heat Transfer Enhancement of a Square Prism

To control the flow around a square prism, a rod was set upstream of the prism. The side length of the prism was 20mm and the diameter of the rod was changed from 2 to 10mm. The spacing between the axes of the prism and the rod was 40 to 100mm. The Reynolds number ranged from 5.3×(10)^3 to 3.2×(10)^4. The relationship between the local heat transfer and the fluid flow around the square prism was investigated. Three flow patterns were observed. The best flow pattern for heat transfer enhancement and drag reduction is the pattern without the vortex shedding from a rod. Changes in the flow pattern depended on the rod diameter, its position and its Reynolds number. The average heat transfer of the square prism increased by 35% compared with the case of the square prism without a rod. The drag coefficient was reduced by about 80%.