Study of Exponential Thermal Boundary Condition on Unsteady Magnetohydrodynamic Convection in a Square Enclosure Filled with Fe3O4- Water Ferrofluid

Abstract

In this paper, magnetohydrodynamic convection is analyzed numerically for a square enclosure filled with Fe3O4-water ferrofluid. A time-dependent exponential thermal boundary condition is applied at the bottom wall of the cavity. The ferrofluid is modeled as a single-phase fluid. Maxwell-Garnet model is used for modeling the effective thermal conductivity and viscosity of the ferrofluid. The Galerkin-weighted residuals method of finite-element analysis is adopted for the numerical solutions. The solid volume fraction,  is varied from 2.5 to 10% and the Hartmann number Ha from 0 to 20. Investigations are carried out for Rayleigh number Ra =10 4 and 10 5 over dimensionless times τ=0.01-1.0. The present study indicates that Ra, Ha and , have a significant effect on heat transfer. At τ =1, if Ra=10 4 , a higher solid volume fraction maximizes heat transfer whereas at Ra=10 5 , a lower solid volume fraction maximizes heat transfer. Moreover, at τ =1, incrementing Ha diminishes heat transfer at Ra=10 4 whereas an optimum value of Ha=10 maximizes heat transfer for Ra=10 5 . The exponential thermal boundary conditions have a certain importance on heat transfer. The present results provide necessary information for further investigation of heat transfer in its different applications.

Heat generation/absorption effect on natural convective heat transfer in a wavy triangular cavity filled with nanofluid

“…Uddin et al 32 studied computational simulation numerically for convective heat flow into nanofluid. Unsteady convective MHD numerical impact of sinusoidal warmed boundary condition with Fe 3 O 4 -water ferrofluid was performed by Alam et al 33 . Al-Asad et al 34 studied hydrodynamics impacts of convective flow using a perpendicular fin within a wavy square cavity.…”