Implementation and assessment of a hybrid RANS/LES model using OpenFOAM

This paper addresses the limitations of the traditional Shear Stress Transport Detached Eddy Simulation (SSTDES) model in simulating complex unsteady turbulence and proposes an enhanced Shear Stress Transport Filtered Detached Eddy Simulation (SSTFDES) model developed using the open-source software Open Field Operation and Manipulation (OpenFOAM). The model introduces unsteady turbulence fluctuations within the boundary layer through adaptive filtering techniques, adjusting the eddy viscosity coefficient ${\nu }_t$ and the blending function $F_{DES}$, thereby improving the model's ability to capture turbulent characteristics. Two high Reynolds number cases were selected for validation: the three-dimensional square cylinder flow at $Re=21400$ and the surface-mounted cube case at $Re=40000$. The improved model was implemented in OpenFOAM and tested to assess its performance in simulating both isolated and infinitely long bluff body configurations. The results demonstrate that the SSTFDES model outperforms the traditional model in capturing wake vortex shedding characteristics, pressure distribution, and lift/drag coefficients, particularly exhibiting higher accuracy and robustness in pressure coherence analysis and vortex shedding frequency prediction. Additionally, energy spectrum and probability density function analyses based on the model's computational results further validate its accurate prediction of the unsteady characteristics of the wake vortex. The study suggests that the SSTFDES model provides new insights for the further development of Hybrid RANS-LES Method (HRLM).