Mathematical properties of the SimpleX algorithm

TL;DR

This paper analyzes the mathematical properties of the SimpleX radiative transfer algorithm, providing error analysis, validation, and improvements to enhance its accuracy and computational efficiency.

Contribution

It offers a detailed mathematical and numerical analysis of SimpleX, introduces enhancements for better accuracy and speed, and discusses necessary modifications for physically correct particle transport.

Findings

Quantitative error characterization of SimpleX

Validation confirms the analytical error predictions

Improvements lead to increased accuracy and computational speed

Abstract

Context. Analytical and numerical analysis of the SimpleX radiative transfer algorithm, which features transport on a Delaunay triangulation. Aims. Verify whether the SimpleX radiative transfer algorithm conforms to mathematical expectations, to develop error analysis and present improvements upon earlier versions of the code. Methods. Voronoi-Delaunay tessellation, classical Markov theory. Results. Quantitative description of the error properties of the SimpleX method. Numerical validation of the method and verification of the analytical results. Improvements in accuracy and speed of the method. Conclusions. It is possible to transport particles such as photons in a physically correct manner with the SimpleX algorithm. This requires the use of weighting schemes or the modification of the point process underlying the transport grid. We have explored and applied several possibilities.