Aerodynamic drag is an important factor in vehicles fuel consumption. Pressure drag which is the main component of total drag is a result of boundary layer separation from vehicle surface. Flow control methods are applied to avoid or at least delay separation. Depending upon whether these methods consume energy to control the flow or not, they are called active or passive control methods. In th...

Smart Morphable Surfaces enable switchable and tunable aerodynamic drag reduction of bluff bodies. Their topography, resembling the morphology of golf balls, can be custom-generated through a wrinkling instability on a curved surface. Pneumatic actuation of these patterns results in the control of the drag coefficient of spherical samples by up to a factor of two, over a range of flow conditions.

Constant rise in fuel price in recent times has caused manufacturers of heavy commercial vehicles (HCV) to turn to efficient aerodynamic design of trucks, wagons, tractors as well as trailers. The comparative analysis in this study compares the coefficient of drag of the following four aerodynamic configurations of a tractor-trailer combination: 1. Semi-trailer with no devices. 2. Semi-trailer ...

This work was one of the tasks of the Manufacturing2Client project, whose objective was to develop a frontal deflector to be commercialized in the automotive industry, using new project and manufacturing methods. In this task, in particular, it was proposed to develop the ability to predict computationally the aerodynamic influence of flow in vehicles, in an effort to reduce fuel consumption in...

Adaptive morphing trailing edge wings have the potential to reduce the fuel burn of transport aircraft. In this paper, we quantify the aerodynamic performance benefits of a morphing trailing using aerodynamic design optimization. The aerodynamic model solves the Reynolds-averaged Navier– Stokes equations with a Spalart–Allmaras turbulence model. A gradient-based optimization algorithm is used i...

This paper discusses the use of control theory for optimum design of aerodynamic configurations. Examples are presented of the application of this msethod to the reduction of shock induced pressure drag on airfoils in two-dimensional transonic flow.

Federal Lab. for Materials Testing and Research (Empa) Dübendorf Switzerland l 5 Bakala Academy Athletic Performance Center Univ. of Leuven Heverlee, Belgium Surprises in cycling aerodynamics T he greatest potential for improvement in cycling speed is aerodynamic” [1]. At racing speeds (about 54 km/h or 15 m/s in time trails), the aerodynamic resistance or drag is about 90% of the total resista...

[1] Recent field and laboratory observations indicate that the variation of drag coefficient with wind speed at high winds is different from that under low-to-moderate winds. By taking the effects of wave development and sea spray into account, a parameterization of sea surface aerodynamic roughness applicable from low to extreme winds is proposed. The corresponding relationship between drag co...