Generation of entropy during forced convection of heat in nanofluid stagnation-point flows over a cylinder embedded in porous media

Abstract

Thermodynamics and heat transfer of an impinging nanofluid flow upon a cylinder with constant surface temperature and embedded in porous media are investigated. Numerical solutions reveal the flow velocity and temperature fields as well as the Nusselt number. These are then used to calculate the rate of entropy generation within the system by viscous and heat transfer irreversibilities. It is demonstrated that changes in the concentration of nanoparticles modify the thermal and hydrodynamic boundary layers and hence can alter the Nusselt number and entropy generation considerably. However, the shear stress on the surface of the cylinder is observed to be less affected by the variations in the concentration of nanoparticles. Further, the Reynolds number and non-uniform transpiration are shown to affect the Nusselt number and entropy generation. It is argued that the influences of Reynolds number on the boundary layer thickness can majorly modify the irreversibility and Bejan number.

Additional information

Funding

N. Karimi acknowledges the partial financial support by EPSRC through grant number EP/N020472/1 (Therma-pump).