Development and validation of a transition model based on a mechanical approximation

TL;DR

This paper introduces a new 3D transition turbulence model based on mechanical approximation, which is more accurate and faster than existing empirical models, validated through benchmark tests and complex flow scenarios.

Contribution

The paper presents a novel 3D transition model based on mean flow shear, validated against multiple benchmark cases and complex flow conditions, outperforming empirical models in accuracy and speed.

Findings

Accurately predicts bypass transition under various conditions.

Successfully models separation induced transition.

Performs well in complex 3D geometries.

Abstract

A new 3D transition turbulence model, more accurate and faster than an empirical transition model, is proposed. The model is based on the calculation of the pre-transitional u'v' due to mean flow shear. The present transition model is fully described and verified against eight benchmark test cases. Computations are performed for the ERCOFTAC flat-plate T3A, T3C and T3L test cases. Further, the model is validated for bypass, cross-flow and separation induced transition and compared with empirical transition models. The model presents very good results for bypass transition under zero-pressure gradient and with pressure gradient flow conditions. Also the model is able to correctly predict separation induced transition. However, for very low speed and low free-stream turbulence intensity the model delays separation induced transition onset. The model also shows very good results for transition under complex cross-flow conditions in three-dimensional geometries. The 3D tested case was the 6:1 prolate-spheroid under three flow conditions.