High-order discontinuous Galerkin RANS solutions of the incompressible flow over a delta wing

Abstract

In this paper, high-order Discontinuous Galerkin (DG) Reynolds Averaged Navier Stokes (RANS) computations of the turbulent incompressible flow over a 65° deg sweep delta wing are presented. The flow regimes and the wing geometric configuration refer to those adopted in the international Vortex Flow Experiment 2 (VFE-2) project (Hummel, 2009) [1]. Here we consider the incompressible case, at Reynolds numbers 106 and 2×106, which has not yet been analyzed in-depth in literature from the numerical point of view. An extensive comparison of our results with experimental data, mainly those obtained by Furman and Breitsamter (2006, 2008, 2009, 2013) [2–5], is here supplied.As regards the turbulence modeling approach, recent researches have revealed that fully-turbulent RANS computations, at Reynolds number greater than 3×106 and at Mach numbers above 0.4, predict the main flow field features correctly.The same behavior was not observed in the incompressible case, however we have found that it is sufficient to fix a turbulent transition, at approximately the 25% of the delta wing root chord, to greatly improve the results quality.The employed transition model is quite simplistic and the resulting simulation approach is not in general completely satisfactory, however the results accuracy establishes the major role of the turbulent transition in predicting the delta wing flow-field. Moreover our solutions fully confirm the interpretation of this flow given by Furman and Breitsamter (2006, 2008, 2009, 2013) [2–5]. Finally, these computations put in evidence the robustness and the effectiveness of our high-order DG solver in dealing with large and complex problems on massively parallel architectures, using up to 4096 CPU cores.