Modeling infinite/axisymmetric liquid metal magnetohydrodynamic free surface flows

Over the past several years, as part of the Advanced Power Extraction (APEX) project, liquid metal magnetohydrodynamic (MHD) film and jet flows have been modeled using the assumption of axisymmetry to simplify the governing equations to a more tractable two-dimensional (2D) form. The results of these 2D simulations as they pertain to liquid wall and divertor flows is presented here. The effect of toroidal field gradient on the flow thickness is shown to be rather small for thin fast first wall (FW) flows on electrically insulated backwalls, but streamwise currents generated by flow across the toroidal field gradient can interact with radial magnetic field components to produce toroidal motion with strong shear across the flow depth. The drag effects from flow across the toroidal field gradients become much stronger if thicker flows are considered. Concerns about surface stability due to forces trying to pull the liquid off the backwall also become much more severe for thicker flows or flows with conducting walls. Plans for continued work with three-dimensional models are discussed.