Hydrothermal performance for forced convective flow of viscoplastic fluid through a backward facing step channel

Abstract

The hydrothermal performance for steady, laminar forced convective flow of viscoplastic fluid through a backward facing step channel is studied. The effect of Bingham number (0 ≤ Bn ≤ 1), Reynolds number (50 ≤ Re ≤ 300), and power law index (0.2 ≤ n ≤ 1) on the thermal and flow characteristics are analyzed. A recirculatory zone is generated at the step corner and the findings depict a decrement in the length of reattachment as n and Bn increases. The temperature drop in the vicinity of the step increases as Bn increases. Also, it is found that the local Nusselt number (Nu) attains a peak in the vicinity of the step and the maximum Nu in this region increases with the increase in Bn. Moreover, for any particular value of Bn, Nu decreases with the increase in n. Also, the average Nusselt number increases significantly for viscoplastic fluids in comparison to shear-thinning and Newtonian fluids, and the heat transfer rate increases as Bn increases. Furthermore, there exists a critical value of Bn that alters the variation of average Nusselt number with the power-law index in case of separated flows.