Frequency-Dependent Material Motion Benchmarks for Radiative Transfer

TL;DR

This paper introduces a benchmark for radiation transfer in moving absorbing slabs, highlighting the importance of material motion corrections and their impact on accuracy in radiative transfer simulations.

Contribution

We provide a general analytical solution for radiation intensity in moving absorbing slabs and demonstrate its use as a benchmark to identify errors in material motion correction implementations.

Findings

Ignoring motion correction terms causes 20-80% errors.

Benchmark helps detect errors in simulation codes.

Errors increase with frequency resolution.

Abstract

We present a general solution for the radiation intensity in front of a purely absorbing slab moving toward an observer at constant speed and with a constant temperature. The solution is obtained by integrating the lab-frame radiation transport equation through the slab to the observer. We present comparisons between our benchmark and results from the Kull simulation code for an aluminum slab moving toward the observer at 2% the speed-of-light. We demonstrate that ignoring certain material motion correction terms in the transport equation can lead to 20-80% errors with the error magnitude growing as the frequency resolution is improved. Our results also indicate that our benchmark can identify potential errors in the implementation of material motion corrections.