[Lecture] Validation of PANS and influence of ground and wheel motion on the aerodynamic behaviors of a van

Speaker: Prof. Sinisa Krajnovic, Head of Department Mechanics and Maritime Sciences, Chalmers University of Technology, Sweden

Time: 10:00, July 4, 2023

Venue: Room 218, A1 Building, State Key Laboratory of Rail Transit Vehicle System, Jiuli Campus, Southwest Jiaotong University.

Abstract:

A numerical investigation of the effects of the moving ground and rotating wheels on the turbulent flow around a scaled square-back van model will be presented. A comparison among the partially averaged Navier–Stokes (PANS), large eddy simulation (LES) and particle image velocimetry (PIV) involving the aerodynamic drag, the wake topology, the velocity and the Reynolds stress profiles in the wake region is conducted. The proper orthogonal decomposition and fast Fourier transform are applied to the shear layers shedding from the trailing edges to comment on the coherent structures and their frequency content. The results show that PANS accurately predicts the flow field measured in experiments and predicted by a resolved LES, even with a low-resolution grid. The superiority of the PANS approach could provide good guidance for industrial research in predicting the turbulent flow around the square-back van model with affordable computational grids. The wheel and ground motion mechanism on the aerodynamic forces has been revealed by analyzing the surface pressure distribution, the wheels’ surrounding flow, the underbody flow characteristics and the turbulent wake structures. The effects of the ground and wheel motion on the frequency, evolution and development characteristics of the wake shear layers are analyzed, providing relevant insights for future experimental investigations of square-back van models.

Biography:

Sinisa Krajnovic is a Full Professor of Computational Fluid Dynamics at Chalmers University of Technology in Sweden. Prof. Krajnovic is the Head of Department Mechanics and Maritime Sciences at Chalmers University of Technology. He has conducted research in automotive aerodynamics in the last 25 years, aiming at improving vehicle performance regarding energy consumption, stability relevant to road and rail safety and other aerodynamic aspects. The core of his research consists of development of unsteady numerical techniques and their applications in road vehicle and train aerodynamics, aerodynamic shape optimization and flow control techniques for improvement of aerodynamic performance of vehicles. Prof. Krajnovic has published more than 200 scientific papers in international scientific journals and reviewed conference proceedings and has more than 4900 citations.