Simulation of the Flow-Field Around a Generic Tractor-Trailer Truck

In the present work computational fluid dynamics (CFD) simulations of the flow field around a generic tractor-trailer truck are presented and compared with corresponding experimental measurements.

A generic truck model was considered which is a detailed 1/8th scale replica of a Class-8 tractor-trailer truck. It contained a number of details such as bumpers, underbody, tractor chassis, wheels, and axles. CFD simulations were conducted with wind incident on the vehicle at 0 and 6 degree yaw. Two different meshing strategies (tet-dominant and hex-dominant) and three different turbulence models (Realizable k-ε, RNG k-ε, and DES) are considered. In the first meshing strategy an unstructured tetrahedral mesh was created over a large region surrounding the vehicle and in its wake. In the second strategy the mesh was predominantly hexahedral except for a few narrow regions around the front end and the underbody which were meshed with tetrahedral cells owing to complex topology. Both steady state and transient simulations were conducted. Transient simulations with the predominantly hexahedral mesh predicted C_D accurately within 1% and 4% of the corresponding experimental value for the 0° and 6° yaw cases respectively. This level of accuracy is consistently obtained with two turbulence models: RNG k-ε, and DES.