MRT-lattice Boltzmann simulation of magnetic field effects on heat transfer from a heater in a C-shaped cavity filled with non-Newtonian hybrid nanofluids

Abstract

The numerical investigation focuses on the phenomenon of the power-law non-Newtonian magnetohydrodynamic (MHD) natural convection heat transfer in a C-shaped cavity that is filled with ethylene glycol-Al2O3 and Cu hybrid nanofluids with a heating block by utilizing the MRT (multiple-relaxation-time) lattice Boltzmann method (LBM). The heating block is maintained in a constant heat flux condition and placed in the middle of the right wall, and the top two right sides are considered as lower temperature conditions. The other walls of the cavity are in the adiabatic boundary condition. Hydro-thermal analysis of nanofluids is performed for different Rayleigh numbers (Ra), power-law index (n), Hartmann numbers (Ha), magnetic field inclination angle (γ), and nanoparticle volume fraction (ϕ). Results obtained from the numerical simulation are presented by plotting streamlines and isotherms, average Nusselt numbers, and velocity temperature. The results found that when the Hartmann number increases average rate of heat transfer decreases. In addition, the average heat transfer rate decreases for the higher value of the power-law index. For nanofluids like a hybrid, Cu, and Al2O3 nanofluids, the average Nusselt number decreases with the increasing values of the power-law index and Ha number. Here heat transfer is higher in Cu than in hybrid and Al2O3 nanofluids. Total entropy is in increasing band decreasing condition due to higher Rayleigh number. Total entropy decreases when the power-law index rises, and for Ra=104,106.

Keywords

• Natural convection
• Non-Newtonian hybrid nanofluids
• Heat transfer
• Heated blocks
• Wall heat flux
• Lattice Boltzmann method