Laboratory experiments permit quantifying the effects of an atmosphere on cratering efficiency by hypervelocity impacts. Three separable processes have been identified: ambient a mospheric p essure, a rodynamic drag, and pr.•ectile-atmosphere interactions. The effect of ambient atmosphere can be described by a dimensionless pressure ratio, P/By/" for a pressure P, target density 8, and impact v...

Enhancing the aerodynamic efficiency of commercial vehicles is gaining increasing importance as it helps to reduce both overall fuel consumption as well as emissions. This paper investigates the advantages offered by a novel fuel-saving device for such vehicles. This device uses a moving surface to impart additional kinetic energy to flow near the roof surface. The additional momentum in the fl...

Experiments are carried out to study static pressure distribution and drag variations over NACA0018 aerofoil and over an automobile dome. Static pressure coefficients are calculated along the chord length for different angles of attack for both the test models and the results are compared. Further, the relationship between coefficient of drag and Reynolds number has been arrived for different a...

Biomechanics plays an important role helping Paralympic sprinters to excel, having the aerodynamic drag a significant impact on the athlete's performance. The aim of this study was to assess the aerodynamics in different key-moments of the stroke cycle by Computational Fluid Dynamics. A world-ranked wheelchair sprinter was scanned on the racing wheelchair wearing his competition gear and helmet...

Numerical methods are not always convergent especially in higher velocities when shock waves are involved. A comparison analysis is performed to study the supersonic flow over conical bodies of three different cross sections circular, elliptic and squircle (square with rounded corners) shaped using  Perturbation techniques to find flow variables analytically. In order to find lift and drag forc...

A mathematical model has been developed to investigate the effect of a sprinkler spray on adjacent horizontal smoke venting and in particular the water droplet drag component. The pressure difference across a roof vent and the volumetric flow of smoke vented are determined by considering the interaction between the drag force of the sprinkler spray and the buoyancy of the smoke layer in the spr...

Extensive wind tunnel tests have been conducted to investigate the unsteady flow field over and behind a 2D model of a 660 kW wind turbine blade section in pitching motion. The surface pressure and wake dynamic pressure variation at a distance of 1.5 chord length from trailing edge were measured by pressure transducers during several oscillating cycles at 3 reduced frequencies and oscillating a...

Direct numerical simulation of turbulent channel flow over a compliant surface has been performed to evaluate the friction drag reduction effect. It is found that a slight drag reduction is observed over a compliant surface. This observation indicates that drag reduction is possible using a compliant surface that is deformed passively by wall pressure fluctuation. A small wall displacement and ...

In competitive swimming, suits have become more important. These suits influence friction, pressure and wave drag. Friction drag is related to the surface properties whereas both pressure and wave drag are greatly influenced by body shape. To find a relationship between the body shape and the drag, the anthropometry of several world class female swimmers wearing different suits was accurately d...