Owen Williams, Madeline Samuell, E. Sage Sarwas, Matthew Robbins and Antonino Ferrante, AIAA SciTech 2020
An experimental and computational investigation of a new turbulent separated flow simulation validation test case at subsonic flow conditions is presented. Through close collaboration with Boeing, a three-dimensional tapered hump or “speed bump” geometry, relevant to a range of aerodynamic applications and central to an integrated testing/CFD campaign to improve turbulent RANS modeling is proposed. This study focuses on an examination of the flow over this geometry, as well as surveys of inflow boundary conditions, allowing the formalization of the domain, geometry and inflow length for corresponding CFD simulations. The analytically-defined geometric shape is tapered at the sides to minimize adverse side-wall flow interactions present in several previous bump experiments. Surface pressure and flow visualizations indicate the presence of moderate three-dimensionality at the centerline of the model but also a regime of Reynolds number independence, which is a desirable property for a validation test case. In contrast, while pressure coefficients computed from RANS simulations have similar magnitude to the experimental results, they fail to capture the Reynolds number insensitivity and profile inflection near reattachment that is observed in the experiments. These results suggest that the chosen geometry provides a strongly separated flow that is a challenging test for current RANS simulation capabilities.