Calibration of CFD Methods for Industrial estimations of Aerodynamic Drag of Ground Based Vehicles under unsteady on-flow conditions

Abstract

We report on the continuation of work presented during the STAB 2022 conference. In the STAB 2022 work it is noted that changes in measured and computed drag match experiments closely if differences between a reference CFD and and a CFD result with small modifications to the computational problem are compared. Using this observation as a prognostic tool it was deduced that inclusion of active/passive suction for boundary layer (BL) control should reduce differences between CFD and measure sufficiently so that the CFD results should more closely replicate the measurements for drag obtained in the SWG tunnel. Inclusion of the aforementioned BL control methods into the CFD model is shown, in the current presentation, to improve the fidelity of the CFD results. Examination of the local flow field about the model reinforce the importance of properly modeling the interaction between the onflow and the train head. For steady onflow conditions the response of the local flow field is localized to the train head and to the initial part of the train underflow.