Numerical Study of GAS method with γ Transition Model

Developing a predictive method that accounts for boundary layer transition and massive separation is crucial for the design of aerospace vehicles. The Grid-Adaptive Simulation (GAS) model, proposed by our previous study based on the Kolmogorov energy spectrum, modifies the turbulence viscosity equations using the ratio of the grid length scale to the turbulent integral length scale, achieving high accuracy in turbulent flow simulations across different grid resolutions. When implemented in ANSYS CFX, the GAS model exhibited commendable performance in simulations of backwardfacing step flows. However, the GAS model, based on turbulence models, tends to delay separation in laminar separation predictions. This paper introduces the RANS-LES-Tr method, the GAS-γ model, based on the γ transition model. The GAS- γ model is validated in cylinder flow with laminar separation, and compared with the GAS model in ANSYS fluent. The GAS-γ model demonstrates notable improvements over the turbulence model-based GAS approach. The grid-adaptive model with transition consideration shows great potential in aerospace design computations, striking a balance between high predictive accuracy and computational efficiency.