Background: In this work, the effect of a uniform magnetic field (UMF) on the natural
convection heat transfer of Cu-water nanofluid in a porous half-annulus cavity is studied by finite
element method, considering heat generation. The effects of four parameters (magnetic field angle
(γ), Hartmann number (Ha), nanoparticles volume fraction (φ) and Rayleigh number (Ra)) on the
local and average Nusselt numbers of outer wall have been investigated.
Methods: Numerical Finite Element Method (FEM) based on FlexPDE commercial code was used to
solve the described problems and the validation was also performed by Finite Difference Method
(FDM) in previous studies.
Results: It was found that by applying external magnetic field with a certain angle with respect to the
geometry, the maximum local heat Nusselt number could shift to one side of outer wall and the shift
is dependent on the angle of the imposed magnetic field.
Conclusion: Our results also confirm that increasing the Hartmann number decreases the Nusselt
number due to Lorentz force resulting from the presence of stronger magnetic field which slows
down the fluid motion and in turn leads to a decreased heat transfer.