Evaluation of commercial CFD code capabilities for prediction of heavy vehicle drag coefficients

In collaboration with the U.S. Department of Energy's Heavy Vehicle Aerodynamic Drag Team, Argonne National Laboratory is developing guidelines for the near-term use of existing commercial computational tools by the heavy vehicle manufacturing industry. These guidelines are being developed based upon measured drag coefficients as well as detailed surface pressure distributions from wind tunnel experiments completed at NASA Ames Laboratory using a generalized 1/8th-scale conventional U.S. tractor-trailer geometry, the Generic Conventional Model (GCM). Studies consider the effects of selection of global and near surface mesh size parameters and selection of turbulence modeling strategies. Initial results indicate that drag coefficients can be predicted within 1 percent of measured values and that reasonable agreement with measured surface pressure distributions can be achieved.