On the Simulation of a Heavy Vehicle Wake in OpenFOAM with Real-World Data

Two computational approaches are taken to characterize the drag of a car driven behind a heavy vehicle under real conditions. The on-road approach uses velocity measurements, obtained from an array of static five-hole probes, to construct on-flow boundary conditions replicating the atmospheric dynamics encountered during an on-road measurement. The wind tunnel approach uses an oscillating flap system to control flow time and length scales upstream of a wind tunnel model. The amplitude and frequency of the flap motion is calibrated to reproduce length and time scales at on-road conditions under respective Reynolds and Strouhal number scaling. These approaches are evaluated against experimental measurements using Computational Fluid Dynamics (CFD) and demonstrates that they reproduce the aerodynamic drag and a significant part of the measured onflow condition for the car.