Downstream wake features of a Rood wing predicted by different turbulence models

Abstract

Computational fluid dynamics is used to analyze the influence of the horseshoe vortex on the wake features of a simplified geometry representing an underwater vehicle sail (i.e. Rood wing). The sail wake features are of interest as they influence the performance of the downstream components of an underwater vehicle such as the aft appendages and propeller. This paper uses the Rood wing, a generic wing body, mounted on a flat plate as its low aspect ratio is comparable to the underwater vehicle sail and there are substantial published experimental data for validation. Two main simulation schemes were adopted in this paper, i.e. the Reynolds-averaged Navier–Stokes (RANS) and hybrid RANS–large Eddy simulation (LES) incorporating several turbulence models. Both schemes were also examined in their ability to predict the downstream wake features as the literature available to date have primarily focused only on the near-field flow features around the wing root. Three main parameters were investigated including the pressure distribution along the wing’s body, the mean streamwise velocity, and its root mean square fluctuation at three different downstream planes, two in the near field and one in the far field. Results show that the RANS and the hybrid RANS–LES models are capable of predicting the wing-body pressure distribution and the paths of the horseshoe vortex (HSV) as it moves downstream with acceptable numerical dissipation. It was found that different models provided higher accuracy when compared to the experiment depending on the downstream location of the plane. The re-normalization group k-epsilon model with enhanced wall treatment (RNG KE-EN) model captured the wake properties with the highest accuracy within the near field, while further downstream (in the far field), the scale adaptive simulation (SAS) model predicted the flow field with the highest accuracy followed by the RNGKE-EN model.