Investigation of differences between wind tunnel and road tests using CFD method in aerodynamic of vehicle

Especially at the present time, inapplicability of aerodynamic performance tests for real conditions is a big problem in vehicle aerodynamics. Performance measurements in road tests and inaccuracy problems in wind tunnel tests have not been fully solved. In this study, problems and effects of these problems on the main aerodynamic performance parameters such as drag coefficient and lift force were investigated. Main problems; vehicle wheel motion, road motion, and both road and wheel motion problems are emphasized. Computational Fluid Dynamics (CFD) method was used in the analyzes performed within the study. Workstation with 48 logical processors and ANSYS FLUENT software which is licensed by Anadolu University and Eskisehir Technical University were used. In this study, all analyzes were performed using Ahmed model. Firstly, CFD analysis of Ahmed model which has physical aerodynamic performance tests have been done, and then, mesh independence and model setup validation studies have been carried out. After these studies, wheel gaps and wheels were constituted on basic Ahmed model. Fixed Model, Wheel Motion Model, Road Motion Model and Wheel-Road Motion Model was prepared and analyzed using the validated model. The differences in the results data of the different situation analyzes and necessity of providing the real conditions in the aerodynamic performance tests and analyzes were evaluated.