Abstract
Flow visualization experiments on Barns effect in a one-sided cavity has been performed in order to develop the heat transfer augmentation technique in a cavity, where heat transfer is reduced for the case of Newtonian fluid. In this paper, the effects of expansion ratio and Weissenberg number in a low Reynolds number region on recirculation length formed in the downstream region of the cavity between ribs. The width of wide flow path and the length of the rib were fixed at 40 and 50mm, respectively, while solvent Reynolds number based on rib height was changed from 100 to 400. The rib height and cavity length were also changed in three steps, respectively. From the results, it is found that the recirculation length in the low Reynolds number range becomes much smaller than that in the case of Reynolds number of 2,400 reported by the previous study. This can prevent heat transfer reduction in the downstream region of the cavity. Then, this technique becomes more effective in low Reynolds number region. It is also found that the recirculation length depends not on expansion ratio but on Weissenberg number in low Weissenberg number region.
