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Research Papers: Fundamental Issues and Canonical Flows

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

[+] Author and Article Information
Subrahmanya P. Veluri1

Department of Aerospace and Ocean Engineering, Virginia Tech, 215 Randolph Hall, Blacksburg, VA 24061veluris@vt.edu

Christopher J. Roy

Department of Aerospace and Ocean Engineering, Virginia Tech, 215 Randolph Hall, Blacksburg, VA 24061

Anwar Ahmed, Rifki Rifki, John C. Worley, Bryan Recktenwald

Department of Aerospace Engineering, Auburn University, 211 Aerospace Engineering Building, Auburn, AL 36849-5338

1

Corresponding author.

J. Fluids Eng 131(8), 081201 (Jul 07, 2009) (9 pages) doi:10.1115/1.3155995 History: Received December 16, 2008; Revised May 13, 2009; Published July 07, 2009

## Abstract

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 $3×4 ft2$ 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.

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## Figures

Figure 2

Schematic of the simplified truck geometry in the wind tunnel

Figure 3

Computational geometry of the simplified tractor/trailer placed in the wind tunnel

Figure 4

Top view of the wind tunnel geometry

Figure 11

Comparison of the Cp variation on the sides of the truck geometry

Figure 12

Comparison of the Cp variation on front of the truck geometry

Figure 1

Flow visualization/force model mounted in the wind tunnel test section

Figure 5

Comparison of boundary layer profiles (a) at 9 in., (b) at 20 in., and (c) at 39 in. from the beginning of the test section

Figure 6

Flow angularity at a vertical center at 9 in. from the beginning of the test section

Figure 7

Computational mesh (coarse grid) for the truck geometry placed in the wind tunnel

Figure 8

Drag convergence on truck

Figure 9

Schematic of the location of the pressure ports on the truck geometry

Figure 10

Comparison of the Cp variation on the top and bottom of the truck geometry

Figure 13

Comparison of the Cp variation on the back of the truck geometry

Figure 14

The velocity contours along with the streamlines on the vertical symmetry plane for the SST k-ω turbulence model

Figure 15

Pressure data comparisons on the back of the trailer

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