Gamma-Theta经验转捩模型在DES中的应用

与RANS湍流模型相比，DES湍流模型的边界层外自由流部分存在LES区，该区域的涡粘性会有所降低。为了研究了这一特征对γ-Reθt转捩模型的影响，以平板实验为算例，选取基于k-w SST湍流模型的DES模型和DDES模型，检验γ-Reθt转捩模型在DES模型和DDES模型中的表现。结果表明：DES模型和DDES模型使转捩位置推迟，SST—DES模型由于对网格过度敏感而没有触发转捩，SST—DDES模型使转捩位置后移较少；DDES模型比DES模型更适合γ-Reθt转捩模型；转捩经验关系需要进行修正后才能将γ-Reθt应用于DDES模型。

Application of Gamma-Theta transition model in DES

The correlation-based transition model was originally developed by Langtry and Menter for use with the two-equation k-w SST turbulence model. DES methods have lower eddy viscosity than RANS method in its LES zone outside the boundary layer, this will affect performance of transition model. The behavior of transition model implemented in DES and DDES model was investigated. The numerical test on flat plate show that DDES method can delay the transition, and in DES method, transition was suppressed by the over-reduced eddy viscosity. This indicated that DDES method is more suitable for implementing of transition model than DES method and recalibration of the transition model is required.