Development of guidelines for the use of commercial CFD in tractor-trailer aerodynamic design

With rising oil prices, the issue of energy economy in transportation is getting much attention. At the same time, new emissions standards for tractor-trailer vehicles introduce additional challenges for the manufacturers to achieve improvements in vehicle fuel economy. As part of the U.S. Department of Energy Office of FreedomCAR and Vehicle Technologies' Heavy Vehicle Aerodynamic Drag Consortium, Argonne National Laboratory is currently developing guidelines for the use of commercial computational fluid dynamics (CFD) software to facilitate energy efficiency improvements through improved aerodynamic design of tractor-trailer vehicles. The development of these guidelines requires the consideration of the sensitivity of the accuracy of the analysis to the various modeling choices available to the end user. Early investigations focused on the sensitivity of the predictions of drag coefficients and surface pressure distributions for the standard configuration of the GCM at zero yaw to the size and structure of the computational mesh and the selection of turbulence model. Current assessments are focusing on the impact of these parameters on simulations of the standard GCM at yaw angles greater than zero.