Joint Computational/Experimental Aerodynamic Study of a Simplified Tractor/Trailer Geometry

Steady-state Reynolds averaged Navier–Stokes (RANS) simulations are presented for the three-dimensional flow over a generic tractor trailer placed in the Auburn University $3×4ft2$ suction wind tunnel. The width of the truck geometry is 10 in., and the height and length of the trailer are 1.392 and 3.4 times the width, respectively. The computational model of the wind tunnel is validated by comparing the numerical results with the data from the empty wind tunnel experiments. The comparisons include the boundary layer properties at three different locations on the floor of the test section and the flow angularity at the beginning of the test section. Three grid levels are used for the simulation of the truck geometry placed in the test section of the wind tunnel. The coarse mesh consists of $3.4×106$ cells, the medium mesh consists of $11.2×106$ cells and the fine mesh consists of $25.8×106$ cells. The turbulence models used for both the empty tunnel simulations and the truck geometry placed in the wind tunnel are the standard Wilcox 1998 $k-ω$ model, the SST $k-ω$ model, the standard $k-ε$ model, and the Spalart–Allmaras model. The surface pressure distributions on the truck geometry and the overall drag are predicted from the simulations and compared with the experimental data. The computational predictions compared well with the experimental data. This study contributes a new validation data set and computations for high Reynolds number bluff-body flows. The validation data set can be used for initial assessment in evaluating RANS models, which will be used for studying the drag or drag trends predicted by the baseline truck geometries.