Numerical Modeling of Liquid Metal Free Surface Response to Large Current Pulses

Liquid metal walls may offer a unique solution to challenges with large heat flux mitigation and tritium production in several fusion concepts that are presently being explored. One such fusion concept that may make use of liquid walls is a Z-pinch, where the current path can travel from the plasma through the liquid electrode rather than a solid conductor. In this work, we perform numerical simulations on liquid metal free surface responses to large current and magnetic field pulses as could be encountered in Z-pinches. The Liquid Metal eXperimental (LEX) from Virginia Tech is used to validate a fluid model that is solved using a general purpose finite volume, implicit, unsteady Reynolds-averaged Navier-Stokes Equations (RANSE) solver with realizable k-$\omega$ shear stress transport (SST) turbulence. The simulation domain is comprised of a two-fluid mixture with a high resolution sharp interface capturing (HRIC) algorithm, which combined with the previously mentioned solver, achieves second order accuracy in space and first order accuracy in time. The simulation makes use of both a hydrodynamic model (where the electromagnetic forces have been approximated) and an electrodynamic model making use of magnetohydrodynamics to study the reaction of the liquid metal to the Lorentz force. A parametric study is also conducted to further explore the free surface response of the liquid metal in regimes that are challenging for the experiment to access.