Analysis of Non-Equilibrium Turbulent Boundary Layers using RANS*

Incorporating the effects of flow history and non-locality in non-equilibrium flows represents the current state-of-the-art in Reynolds-Averaged Navier-Stokes (RANS) modeling for practical applications. This study investigates the performance of RANS models for three non-equilibrium turbulent boundary layers of Gungor et al. (IJHFF (2016), 59:109-124; JFM (2022), 948:A5; arXiv:2402.13067). Two of the flows are subjected to an adverse pressure gradient (APG), one of which includes a separation bubble. The third flow transitions from an upstream APG section to a downstream favorable pressure gradient section. The flows are analyzed using RANS simulations with eddy-viscosity-based models and Reynolds stress models, and results are compared with the DNS data of Gungor et al. Preliminary RANS results exhibit qualitative agreement with DNS data. Ongoing work focuses on the detailed analysis of history effects and their impact on model performance. These investigations aim to enhance the understanding and accuracy of RANS models for non-equilibrium turbulent flows.