Analysis of Heat Transfer and Entropy Generation During Natural Convection in a Cu–Water Nanofluid-Filled Porous Cavity for Different Thermal Boundary Conditions

Abstract

The effect of three different thermal boundary conditions on fluid flow, entropy generation and heat transfer is analyzed for natural convection in a closed square porous cavity. The generalized lattice Boltzmann method (based on Brinkman–Forchheimer-extended Darcy model) is used to simulate the flow through the porous medium. The three different cooling arrangements are made at the vertical walls of the cavity via uniform, sinusoidal and linear temperature distributions while maintaining the bottom wall uniformly heated and the top wall thermally insulated. The comparison is carried out with existing published results to lend legitimacy to the findings. Numerical simulations are carried out for the range of Rayleigh number (Ra) from 103 to 105 and Darcy number (Da) from 10−1 to 10−5 with porosity (e) at 0.5. The volume fractions (\(\phi\)) of Cu nanoparticles in water are varied from 0 to 5% to check the influence of nanofluid on the enhancement of heat transfer efficiency. The entropy generation minimization (EGM) approach, based on heat transfer rate and entropy generation, is implemented in order to make a judicious choice of boundary condition in terms of energy efficiency. The results indicate that the selection of optimum boundary condition depends on the values of Ra and Da.