Numerical Investigation of Fluid Flow and Heat Transfer Characteristics over Double Backward-Facing Step with Obstacles

Abstract

Many engineering device, including nuclear reactors, heat exchangers, and electronic circuit boards, exhibit flow separation and reattachment. To reduce thermal stress impacts, the components of these devices, which resemble stepped channel designs and are susceptible to high heat flux, must be properly cooled. The present work numerically investigates the fluid flow and heat transfer characteristics through a double backward-facing step with elliptic obstacles located after each step. For this purpose, equations governing fluid flow and heat transfer are solved in a Cartesian framework using an in-house code based on streamline upwind/Petrov-Galerkin finite element method. The effect of various parameters (axis ratios (0.25, 0.5, 0.75, 1), vertical location of obstacles (0.38, 0.577, 0.769), Reynolds number (300, 500, 800, 1000)) on fluid flow and heat transfer characteristics in the channel with and without obstacles are compared and quantified. The recirculation region length of the double backward-facing stepped channel with obstacles decreases after the first and second steps when compared with no obstacles. The local Nusselt number distribution along the corner regions of the stepped wall is enhanced due to obstacles. The axis ratio of obstacles has less influence on the convective heat transfer enhancement than the vertical location of the obstacles.

Acknowledgments

The numerical simulations were carried out on the Virgo Super Cluster at the High-Performance Computing Environment Facility, Indian Institute of Technology Madras. The authors would like to thank the P.G. Senapathy Centre for Computing Resource, I.I.T. Madras, for providing the facilities required to run the numerical simulations.

Additional information

Notes on contributors

Vishnu Mohankumar

Vishnu Mohankumar is a Ph.D. scholar at the Department of Applied Mechanics, Indian Institute of Technology Madras. His research area is fluid flow and heat transfer characteristics in separating channels using the finite element method.

Karaiyan Arul Prakash

Karaiyan Arul Prakash is a Professor at the Indian Institute of Technology Madras. He obtained his Ph.D. degree in Thermal Sciences from the Indian Institute of Technology Kanpur. His research interests are computational fluid dynamics and heat transfer, cooling technologies, thermal hydraulics, large-eddy simulations and related techniques.