CFD ANALYSIS OF CAR BODY AERODYNAMICS INCLUDING EFFECT OF PASSIVE FLOW DEVICES – A REVIEW

Abstract

With the emphasis lying on increasing fuel efficiency of vehicles in order to combat rising fuel prices and environmental challenges the manufacturers are thinking beyond the conventional vehicle systems by focusing on its aerodynamics. Aerodynamic drag exceeds 50 per cent of the total resistance to motion at speeds above 70km/hr, and above 100 km/hr it is the most important factor. The review is done to identify the various shortcomings of the automotive designers when it is in regards to flow separation of air at the rear of the vehicle which causes most of the losses. This paper focuses on the work already done in the field of aerodynamics starting with Ahmed Body. It is a bluff body with adjustable rear slant angle and the basis upon which the aerodynamicists test their models. And then, moving onto passive aerodynamic enhancements for automobiles like vortex generators and diffusers whose various dimensional modulations were discussed with several steps leading to its advancement in vehicle body design. This brings to the simulation, Computational Fluid Dynamics (CFD) and its role in this analysis was covered. CFD has been modified a lot from the beginning to increase the accuracy of its predictions. So the paper lists various simulation techniques studied by the previous researchers in order to understand the wake region behind the car which has been notoriously difficult to predict till date. Several aspects of aerodynamic drag that need further analysis to improve the aerodynamic were highlighted.