Hybrid RANS/LES Simulations for Flow Around Two Turret Configurations

Abstract

Both hybrid Reynolds Averaged Navier-Stokes (RANS)/ implicit Large Eddy Simulation (ILES) and k− based unsteady RANS (URANS) simulations were performed for flow over two turret configurations. The hybrid RANS/ILES computations were obtained using a well-validated high-order solver employing a 4-order compact spatial discretization in conjunction with a 6-order low-pass spatial filter operator that regularized the evolving solution by selectively removing unresolved high-frequency content. The URANS simulations were accomplished using a k− turbulence model with a 2-order Navier-Stokes flow solver. The first configuration modeled an experiment of a 1 1 2 ” turret at flow conditions of M∞ = 0.5 and ReD = 4.36× 10. The second configuration modeled a one-foot turret at flow conditions of M∞ = 0.4 and ReD = 2.4 × 10. URANS and hybrid RANS/ILES simulations were performed on both configurations using a coarse four-million point mesh. Hybrid RANS/ILES simulations were also conducted on a fine 23 million point mesh. Results from the numerical simulations are compared with experimental pressure, velocity and surface-flow visualization. Independent of the mesh resolution and approach, the numerical simulations for the first turret configuration predicted separation from the turret dome downstream of the experimental location. This result suggests that URANS and hybrid turbulence models were unable to properly simulate the laminar/transitional separation. The simulations at higher Reynolds numbers for the second turret configuration yielded much better agreement with experimental data. The fine-mesh hybrid RANS/ILES solution agreed well with experimental pressure coefficient profiles and was within 3 of the separation angle. For both configurations the hybrid RANS/ILES solutions display complex 3-D flow phenomena in the wake of the turret that the k− URANS model was unable to resolve. The extent that these resolved flow structures degrade and distortion optical wavefronts will be the subject of future research.