Entropy generation analysis of nanofluid forced convection in MHD plane diffuser

Abstract

Fluid flow and forced convection heat transfer inside a plane diffuser with Cu–water nanofluid in the presence of magnetic field is numerically studied with the finite volume method. The steady nanofluid flow is assumed incompressible, laminar, and Newtonian. The cooling nanofluid with low temperature enters the diffuser with constant wall and higher temperature. The influence of Reynolds number (100 < Re < 500), Hartmann number (0 < Ha < 10), and volume fraction of nanoparticles (0 < $\varphi$ < 0.05) on the local and average Nusselt numbers, skin friction coefficient, dimensionless velocity and temperature profiles, total entropy generation, static pressure variation, and pressure recovery coefficient are examined. The results show that increasing the volume fraction of nanoparticles, Reynolds, and Hartmann numbers would increase the total entropy generation and average Nusslet number. In contrast, the pressure recovery coefficient of diffuser decreases by increasing the Reynolds and Hartmann number. Furthermore, numerical results show that, for each Reynolds number there is a critical Hartmann number. So that, the effect of the nanoparticle addition on the pressure recovery coefficient in all Reynolds number is depended to the flow Hartmann number and its value relative to the critical Hartmann number.