Comparison of experimental and numerically obtained flow properties of a bluff body

Abstract

The expected road transport demand in the next twenty years and the increasing environmental constraints together with the rising fuel prices has renewed the interest in truck design; any reduction in truck fuel consumption can be associated with large annual fuel cost reduction and considerable emission savings. Within the development of aerodynamic solutions numerical analysis tools, based on RANS equations, are often used to indicate flow phenomena and characteristics to design low drag bluff bodies. The presented work will discuss the similarities, but mainly the differences between wind tunnel experiments and the time-averaged numerical analysis. Rear pressure distributions are completely different when the numerical outcome is compared with the wind tunnel experiments. The CFD analysis of the boundary layer thickness is within acceptable resemblance with the wind tunnel measurements and the analytical power law model results. Stereoscopic PIV results show different wake structures.