Improvement of Delayed-Detached Eddy Simulation Applied to Separated Flow over Missile Fin

Abstract

This paper presents computational simulations of the flow over a 50-deg sweep missile fin for an angle of attack equal to 25 deg. For such an angle of attack, the flow is expected to fully separate. Nevertheless, Reynolds-averaged Navier-Stokes computations still predict the presence of a leading-edge vortex. Then, hybrid Reynolds-averaged Navier-Stokes/large eddy simulation methods are assessed. In particular, this study focuses on the delayed-detached eddy simulation and on a proposed extension of this method (EDDES), in which the objective is to accelerate the destruction of the eddy viscosity in large eddy simulation regions. These two methods are assessed in the case of a boundary-layer flow, and it is shown that the extended delayed-detached eddy simulation behaves as the delayed-detached eddy simulation method. Nevertheless, in the case of a fully separated flow downstream from a backward facing step, the resolved fluctuations obtained with the extended delayed-detached eddy simulation method are in better agreement with the experimental data than those of the delayed-detached eddy simulation computation. Finally, these two methods improve the description of the flow over the missile fin, predicting a fully separated flow. However, the extended delayed-detached eddy simulation ensures a faster development of instabilities than the delayed-detached eddy simulation and the agreement with the pressure distribution obtained with pressure sensitive paint is much better with the proposed modification of delayed-detached eddy simulation.