Influence of Turbulence Modeling In Capturing Separated Flow Over Delta Wing At Subsonic Speed

Abstract

The visualization of three-dimensional coherent structures present in fluid flow over a delta wing configuration is a challenging task for current CFD research. These turbulent structures have to be resolved by using proper turbulence modeling with combination of computational speed and accuracy for high angles of attack aerodynamic design. With this aim, fully structured grids on a half span delta wing were generated with the grids refined near the wall to capture the physics of vortex flow in both the span- and stream-wise directions. The onset of flow separation and the amount of flow separation have been under-predicted by SA, Standard k-ε and RNG k-ε turbulence models. The primary vortex suction peak is situated conically on the wing and diminishes in magnitude as the trailing edge is approached. The cutting plane technique was utilized for the visualization of vortex breakdown phenomenon at high angles of attack. On the basis of comparison of computed surface pressure plots with that of experimental data and visualization of different contours, Shear Stress Transport model (SST) is found to be a good choice for prediction of separated flow over delta wing configurations. Moreover, surface flow visualizations have shown profound sensitivity of the vortex structures to the angle of attack.