MAGNETOHYDRODYNAMIC MIXED CONVECTION OF NANOFLUID IN A CHANNEL WITH FINITE THICK WALL OPEN CAVITY

Abstract

Heat transfer enhancement in the presence of a magnetic field on conjugate mixed convective flow of nanofluid in a channel with finite thick wall open cavity has been investigated numerically. The fluid enters the channel with a uniform velocity with the bottom wall cavity being at a higher temperature than that of the inlet temperature while the rest of the wall is adiabatic. The physical domain is filled with water-based nanofluids containing Cu nanoparticles. The fluid enters from the left with an inlet velocity and temperature and exits on the right side. In addition to that, different types of thermal boundary conditions are applied along the bottom wall. The governing equations and boundary conditions are transformed into non-dimensional forms and solved by using a finite element method (FEM) based on Galerkin weighted residuals. The studied parameters include dimensionless value of the thermal conductivity (0.05≤K≤1.31), Hartmann number (0≤Ha≤20), Solid volume fraction (0.01≤ϕ≤0.15), Reynolds number (50≤Re≤500), and Richardson number (0.1≤Ri≤10). Different types of characteristics such as streamlines, isotherms, and heat transfer rate in terms of local Nusselt number (〖Nu〗_L), average Nusselt number (〖Nu〗_av), and average fluid temperature (θ_av) are represented for the previously mentioned parameters. It is found that heat transfer is an increasing function of dimensionless thermal conductivity ratio. The results demonstrate that the mentioned parameters strongly affect the flow pattern and temperature field inside the open cavity whereas in the channel these types of effects are less significant.Comparisons with previously published work are made and the results are found to be in excellent agreement. At τ=1, with the increase of Ri from 0.1 to 10, Nu_av increases by 8.76%. If nondimensional time increases, then Nu_av decreases.