A novel local-variable-based Reynolds-averaged Navier–Stokes closure model for bypass and laminar separation induced transition

• Published in: Physics of fluids (1994) 2021-10, Vol.33 (10)
• Main Authors: Li, Yi, Xu, Jiakuan, Qiao, Lei, Zhang, Yang, Bai, Junqiang
• Format: Article
• Language: English
• Subjects: Direct numerical simulation; Flat plates; Fluid dynamics; Fluid flow; Low pressure; Mathematical analysis; Navier-Stokes equations; Pressure gradients; Reynolds averaged Navier-Stokes method; Separation; Shear stress; Turbines; Turbulence intensity; Turbulence models; Turbulent flow
• ISSN: 1070-6631; 1089-7666
• DOI: 10.1063/5.0066007

A one-equation Reynolds-averaged Navier–Stokes closure model is established for bypass transition in this paper. A new local indicator is proposed to describe the variation of turbulence intensities and pressure gradients. Based on this new indicator, a novel and efficient transition criterion is formulated. For laminar separation bubble induced transition, a reasonable modified intermittency factor is developed to complete the reattachment process and control the size of separation bubbles. Incorporated with Menter's k − ω shear stress transport turbulence model, the new transition-turbulence model is built for a high turbulence intensity environment. Several classical flow cases, including the ERCOFTAC (European Research Community on Flow, Turbulence and Combustion) series flat plates with various pressure gradients, the Pratt and Whitney low pressure turbine cascade, and a highly loaded linear compressor cascade, are all employed for the model verifications. Decent agreement with the experimental data and direct numerical simulation data can be obtained in a wide range of incoming flow conditions.