Effects of Turbulence Modeling on RANS Simulations of Tip Vortices

Abstract

of turbulence modeling on the simulations of vortical wake flows using Reynolds-Averaged Navier-Stokes (RANS) equations have been quantified. All the numerical results reported here have been obtained by commercial software (Fluent V 6.3). The roll-up of the near wake of a rectangular wing is investigated using two turbulence models: full Reynolds stress model and Sparlart-Allmaras model. Simulations with the full Reynolds stress model show remarkable mean flow agreement in the tip vortex and spiral wake due to the proper prediction of a laminar vortex core. Simulations with the Spalart-Allmaras model predicted over-diusion of the tip-vortex. The wake of a circulation control (CC), via Coanda eect, of circular planform wing is also investigated using RANS equations and full Reynolds stress model. The streamwise roll up of the trailing vortex wake is delayed in comparison to that of a wing without CC at the same lift. The vortical wake of an isolated helicopter rotor in hover is also simulated using RANS equations and Spalart-Allmaras turbulence model. Results show proper qualitative resolution of the interaction between the shear layer and the spiral tip vortex.