Effect of the spatial change in the electric conductivity of the sub-channel walls on the imbalance of MHD flows

This numerical study analyzes the characterisitics of three-dimensional liquid metal (LM) magnetohydrodynamic (MHD) flows, with combined internal heat generation and wall heat transfer, in a manifold under a uniform magnetic field by using commercial code CFX. The current study investigates the effect of the distribution of the electric conductivitity of the duct walls on the flow imbalance among the sub-channels in the manifold system made up of three sub-channels. In the manifold, the uniform heat generation in the fluid stream and the uniform heat flux on one side wall (parallel to the magnetic field) are applied. Here, the mechanism causing the imbalance in mass flow rate (and in energy flow rate) is clearly discussed. In the fluid region surrounded by the walls with lower electric conductivity, a large electric potential difference and higher velocity are obtained, causing a high mass flow rate and energy flow rate therein, allowing an effective cooling in regions with higher heat load in the blanket. In addition, the interdependency of the current, electric potential, velocity, pressure gradient and temperature of LM MHD flows in the manifold is described in detail.