Three-dimensional MHD flow and heat transfer in a channel with internal obstacle

The magnetohydrodynamic flow and heat transfer of a liquid metal in a channel past a circular cylinder with walls of non-uniform conductivity were investigated. The applied magnetic field was transversal to the forced flow (x-direction) and coplanar with the obstacle, featuring non-null components in both the z- and y-directions. Moreover, the cylinder was displaced by the duct centreline toward the bottom wall and its surface was at uniform temperature, so that a ΔT was present between the obstacle and the fluid at the inlet. Non-uniform thickness for the duct-bounding walls is considered which leads to the promotion of jets close to the less-conductive surfaces. The flow features and heat transfer for this case were numerically investigated for different values of the Reynolds number (20 ≤ Re ≤ 80) and Hartmann number (0 ≤ Ha ≤ 100). Their effects on the flow features, pressure drop and heat transfer are analysed and discussed in detail in the present paper. The additional pressure drop introduced by the cylinder presence is found to be independent by Re and decreasing with Ha. Enhanced heat transfer is observed for an increasing Ha with NuMHD/Nu = 1.25. at Ha = 100 due to the augmented mass flow rate in the bottom sub-channel.