Numerical analysis of nanofluid transportation in porous media under the influence of external magnetic source

•Nanoparticles transportation in a porous semi annulus is examined.•Variable magnetic field effect on hydrothermal behavior is considered.•CVFEM is applied to solve the governing equations.•Nu increase with increase of Ra and Da.

This article is made to examine the impact of external magnetic source on Fe3O4-water ferrofluid convective heat transfer in a porous cavity. The solutions of final equations are obtained by Control volume based finite element method (CVFEM). Graphs are shown for various values of Darcy number (Da), Fe3O4-water volume fraction (ϕ), Rayleigh (Ra) and Hartmann (Ha) numbers. Results indicate that augmenting in Hartmann number results in reduce in velocity of nanofluid and augment the thermal boundary layer thickness. Adding nanoparticles in the based fluid is more effective for higher values of Hartmann number and lower values of Darcy number.