Interface-preserving numerical methods for radiation hydrodynamics

Robust simulation of multi-physics phenomena, such as those found in experiments at the National Ignition Facility, require foundational numerical methods to model accurately. The design process is necessarily enhanced by the use of these numerical simulations due to the high cost of the experiments. This work addresses a challenge in numerical radiation-hydrodynamics in the infinite limit of opacity and perfect isotropy: spurious pressure wave generation at material interfaces. Even without interfacial perturbations or driving forces, non-physical pressure waves can emerge at material interfaces and propagate throughout the domain. For applications like Rayleigh-Taylor Instability studies—where small perturbations can dramatically alter system evolution—these artifacts compromise solution fidelity and limit the method's utility for more complex multi-material, multi-physics simulations. We implement an interface-preserving criterion based on Abgrall's 1996 approach, adapted for the simplified radiation-hydrodynamics equations. This capability provides the numerical foundation necessary for accurate multi-physics simulations involving complex material interactions, shock-interface coupling, and other phenomena critical to inertial confinement fusion and astrophysics applications.