On the Influence of Turbulence Modeling on Steady and Unsteady Flows

Abstract

In analysis of recent numerical solutions of the flow about quite complex geometries, such as e.g. a full aircraft in landing configuration, one can find reasonable agreement with available experimental data. However, it is often difficult to simulate much simpler configurations, especially in the transonic regime, with sufficient accuracy (compared to the experiment). The main source of the discrepancies found is usually the turbulence model, which often fails once stronger transonic phenomena are present. The presence of a strong Shockwave in a turbulent flow has a significant influence on the development of the turbulence field in the region of the shock, as well as the mean flow properties mainly downstream of the shock discontinuity. Thus standard models require special modifications in order to handle the high pressure gradients and the often resulting separation in a consistent and physically realistic way. This becomes even more problematic for unsteady flows, e.g. a pitching airfoil, where good agreement in the steady case is a prerequisite, but no guarantee for good unsteady results when shock b.1. interaction with and without separation is present.