Numerical investigations of fluid flow and heat transfer in double forward facing step in the presence of a fin

Abstract

Fluid flow overstep has many interesting physics such as flow separation, reattachment, recirculation, development of wall boundary layer, and primary and secondary vortices are few of them. Numerical simulation of this situation has been successfully employed for more than 3 decades. In the present investigation, a fin is introduced in the flow passage and explored its role in fluid flow and heat transfer. A fin is attached either to the top wall or bottom wall is considered and its position and size are varied. Further Reynolds number is also varied by assuming the flow is turbulent. Commercial software ANSYS Fluent is used for conducting the numerical simulation. For all the cases results were reported for flow physics and heat transfer in terms of streamline contour, isotherm, local Nusselt number as well as average Nusselt number. It is observed that the local Nusselt number is varied to a maximum value and further is decreased in the downstream direction. By varying the Reynolds number average Nusselt number can be improved from 20% to 85%. The fin size influences to increase of the average Nusselt number if it exceeds 0.3H. However, beyond a certain distance, the location of the fin is less influenced for improving the average Nusselt number. 22% hike in average Nusselt number is achieved when fin is located at top wall when compared to no fin case. However, the peak Nusselt number always occurred at the reattachment of the primary vortex.