Hybrid turbulence model simulations of hemisphere-cylinder geometry

摘要

When low aspect ratio geometries such as submarines, torpedoes, or missiles are operated at large angles of attack three-dimensional separation will occur on the leeward side. Separation incurs losses and can result in undesirable unsteady forces. An improved understanding of three-dimensional separation is desirable as it may open the door to new methods for the control or prevention of separation. Numerical simulations of three-dimensional separation can provide detailed insight into instability mechanisms and the resultant flow structures. For most technical applications the Reynolds numbers are too high for direct numerical simulations and lower-fidelity approaches such as hybrid turbulence models become attractive. In this paper a hybrid turbulence model blending strategy is employed that adjusts the model contribution according to the local grid resolution. The strategy is validated for two-dimensional plane channel flow at Re-tau = 395 and 2000. The model is then employed for simulations of a hemisphere-cylinder geometry at 10 degrees and 30 degrees angle of attack. The simulations demonstrate satisfactory model performance over a wide range of Reynolds numbers (5 x 10(4) < Re-D <5 x 10(5)). A nose separation bubble is captured for the lower Reynolds numbers and leeward vortices are observed for 30 angle of attack regardless of Reynolds number. (C) 2015 Elsevier Inc. All rights reserved.