New capabilities for faster, higher fidelity simulations in HYDRA*

We discuss several new capabilities in HYDRA which enable higher fidelity simulations which also complete faster. A multi-resolution advection method avoids small time step limits near mesh singularities. We show examples where it enables high resolution capsule simulations to complete in just a fraction of the previous run time. A linear response matrix (LRM) method for non-local thermodynamic equilibrium (NLTE) now enables tabular NLTE opacities and equations of state. For hohlraum simulations in which steady state NLTE is a good approximation, LRM tables largely eliminate the time spent calculating NLTE kinetics inline. This enables hohlraum simulations to complete significantly faster and allows NLTE models of any level of complexity to be used. Several improvements to HYDRA’s polar S_N multigroup radiation transport method enable higher accuracy on complex meshes. A novel unlocked-step method is combined with the existing differencing operator to minimize oscillations and improve accuracy in high optical depth zones. A Positivity Preserving Method ensures non-negative solutions in all circumstances and enables faster convergence to solution.