Experimental and Numerical Study of the Aerodynamic Behaviour of a Simplified Road Vehicle

Abstract

Understanding ground vehicles aerodynamics allows us to optimize the operation of a wide spectrum of road vehicles, that ranges from road passenger transport (cars, buses, trains) to road comercial transport (trucks and trains). Within the first group, the so called “double-deck buses” have awakened an increasing interest, given their extensive utilization in our country. According to this, a series of investigations were initiated at the CIMEC (Centro Internacional de Métodos Computacionales en Ingeniería) focussing in the modeling and the understanding of the aerodynamic characteristics of these large vehicles.
As part of an early stage of these investigations, we present in this paper both, numerical and experimental simulation of wind flow passing through vehicles. A simplified model, knowing as Ahmed body was studied and the drag of the model and pressure coefficients on the model rear end were compared between both techniques.
Coupling the wind field with the vehicle dynamics will be the next step in the investigations so a discussion about how to implement Fluid-Structure Interaction (FSI) to this specific problem is also provided.
The numerical model was implemented using PETSc-FEM, which is an open source CFD (Computational Fluid Dynamics) tool based in the Finite Element Method (FEM) using distributed processing and object oriented programming, developed at the CIMEC (http://www.cimec.org.ar/petscfem). The experimental tests were developed in the “Jacek Gorecki” boundary layer wind tunnel, located in the Facultad de Ingeniería de la Universidad Nacional del Nordeste (UNNE) sited in Resistencia, Chaco, Argentina.