UNSTRUCTURED LARGE EDDY SIMULATION OF FLOWS AROUND AUTOMOBILES USING HIGH PERFORMANCE COMPUTING TECHNIQUE: A SHIFT FROM STEADY TO UNSTEADY AERODYNAMICS

摘要

Unstructured Large Eddy Simulation (LES) of flow around vehicles is conducted on the Earth Simulator in Japan. The main objective of our study is to look into the validity of LES for the assessment of vehicle aerodynamics, especially in the context of its possibility for unsteady or transient aerodynamic forces. Firstly, the aerodynamic LES proposed is quantitatively validated on a simplified vehicle. Then, the method is applied to a full-scale production vehicle to investigate the capability of capturing organized flow structures around the vehicle. Finally, unsteady aerodynamic forces acting on the vehicle in transient yawing-angle change are estimated. As a result, it is demonstrated that LES will be a powerful tool for the vehicle aerodynamic assessment in the foreseeable future, because it can provide precious aerodynamic data which conventional wind tunnel tests or RANS simulations are difficult to provide.