Interaction between magnetic field and fluids is crucial in Z pinch process. Since Z pinch involves with multi materials and severe deformation, we develop 3D compatible Lagrangian staggered and cell-centered schemes for ideal MHD on unstructured meshes. Both of the schemes are of first order in space and time discretization. Accuracy and robustness of the schemes are validated with typical numerical tests.

A sound speed distribution-based rezoning strategy is introduced for optimizing deformed Lagrangian grid in arbitrary Lagrangian Eulerian fluid computational methods which includes sound speed distribution-based grid relaxation functional, derivation, discretization and solution of modified gradient flow equations, conditions for starting/terminating grid optimizing procession based on subzonal time step, and algorithm of ALE method based on the new rezoning strategy. Advantage of the method is that it not only optimizes geometry form of grid but also improves time step of Lagrangian hydrodynamic computation. Numerical examples which include ALE calculations of Rayleigh-Taylor instability problem are given to show effectiveness of the strategy.

An artificial viscosity splitting strategy for Lagrangian algorithm of two-dimensional three-temperature radiation magnetohydrodynamics is proposed to solves unphysical pinnacle problem in ion temperature around shock wave as edge viscosity and tensor viscosity are used. The strategy divides kinetic ernergy dissipated by artificial viscosity between electron interior energy and ion interior energy according to ratio of electron pressure and ion pressure. It is realized in two-dimensional three-temperature radiation magnetohydrodynamics code MARED and is used to simulate imploding process of Z-pinch. Unphysical pinnacle in ion temperature around shock wave is removed.

Computing methods for perturbation corner forces in electron pressure,ion pressure and photon pressure are investigated.We propose two kinds of subzonal pressure method for Lagrangian algorithm of two-dimensional three-temperature radiation hydrodynamics.Numerical tests show that both methods work well in eliminating unphysical deformation of Lagrangian mesh.