Validation methodologies for turbulent variable density flows: A jet case study

TL;DR

This paper introduces a formal validation methodology for turbulent variable density flows, applying it to jet simulations and comparing results with experimental data to quantify agreement and identify resolution issues.

Contribution

It demonstrates a structured validation framework for turbulent flow simulations, moving beyond visual comparisons to quantitative assessment using validation metrics.

Findings

Simulation spreading rates exceeded experimental values due to resolution limitations.

Validation metrics effectively quantified the differences between simulations and experiments.

The methodology provides a systematic approach for validating turbulent flow models.

Abstract

Comparisons studies between simulated variable density turbulent flows often consist of direct graphical representations where the level of agreement is determined by eye. This work demonstrates a formal validation methodology using an existing validation framework to examine the agreement between a simulated variable density jet flow and corresponding experimental data. Implicit large eddy simulations (ILES's) of a round jet and a plane jet with density ratio $s = 4.2$ were simulated using the compressible hydrodynamic code xRAGE. The jet growth, characterized by the spreading rates, was compared, and the difference between the simulations and the experiment was examined through jet structure diagnostics. The spreading rates were found to be larger than the experimental values, primarily due to resolution issues in the simulations, a fact that is quantified by the validation metric analysis.