The Application of Eddy-Viscosity Stress Limiters for Modeling Cross-Flow Separation

The ability of eddy-viscosity models to simulate the turbulent wake produced by cross-flow separation over a curved body of revolution is assessed. The results obtained using the standard $k−ω$ model show excessive levels of turbulent kinetic energy $k$ in the vicinity of the stagnation point at the nose of the body. Additionally, high levels of $k$ are observed throughout the wake. Enforcing laminar flow upstream of the nose (which replicates the experimental apparatus more accurately) gives more accurate estimates of $k$ throughout the flowfield. A stress limiter in the form of Durbin’s $T$-limit modification for eddy-viscosity models is implemented for the $k−ω$ model, and its effect on the computed surface pressures, skin friction, and surface flow features is assessed. Additionally, the effect of the $T$-limit modification on both the mean flow and the turbulent flow quantities within the wake is also examined. The use of the $T$-limit modification gives significant improvements in predicted levels of turbulent kinetic energy and Reynolds stresses within the wake. However, predicted values of skin friction in regions of attached flow become up to 50% greater than the experimental values when the $T$-limit is used. This is due to higher values of near-wall turbulence being created with the $T$-limit.