Bluff bodies moving in a fluid experience a drag force which usually increases with velocity. However in a particular velocity range a drag crisis is observed, i.e., a sharp and strong decrease of the drag force. This counterintuitive result is well characterized for a sphere or a cylinder. Here we show that, for an object breaking the up-down symmetry, a lift crisis is observed simultaneously ...

The distribution of dynamic pressure behind a Harris' hawk's wing was sampled using a wake rake consisting of 15 pitot tubes and one static tube. The hawk was holding on to a perch, but at an air speed and gliding angle at which it was capable of gliding. The perch was instrumented, so that the lift developed by the wing was known and the lift coefficient could be calculated. The mean of 92 est...

Using 3D infrared high-speed video, we captured the continuous wing and body kinematics of free-flying fruit flies, Drosophila melanogaster, during hovering and slow forward flight. We then 'replayed' the wing kinematics on a dynamically scaled robotic model to measure the aerodynamic forces produced by the wings. Hovering animals generate a U-shaped wing trajectory, in which large drag forces ...

This study is inspired by the flapping motion of natural flyers: insects. Many insects have two pairs wings referred as tandem wings. Literature review indicates that effects wing are influenced parameters such stagger (the stream-wise distance between aerodynamic center front and rear airfoil), angle-of-attack flow velocity. As a first stage, this focuses on (St) performance A recent numerical...

Today, it is very usual to see numerous cars, from commercial cars to sports cars fitted with different types of spoilers on them. The exterior fashioning and aerodynamically well-organized design for reduction of engine load which reflects in the reduction of fuel consumption and producing the down force for the stability are the two essential factors for an effective operation in the modest w...

By combining the aeroelastic and vortex-forced flutter modes of a thin plastic strip, its oscillation frequency can be confined to scale monotonically with fluid velocity. This principle has been used to produce a low-cost, mm-scale anemometer that measures air speed to ±(5% + 0.5m/s) from 118m/s. The device uses a 2mm slot-type photointerrupt detector to monitor the fundamental frequency of a ...

We consider the problem of solving numerically the stationary incompressible Navier-Stokes equations in an exterior domain in two dimensions. For numerical purposes we truncate the domain to a finite sub-domain, which leads to the problem of finding so called “artificial boundary conditions” to replace the boundary conditions at infinity. To solve this problem we construct — by combining result...

Abstract The blended-wing body is an aircraft configuration that has the potential to be more efficient than conventional large transport aircraft configurations with the same capability. However, the design of the blended-wing is challenging due to the tight coupling between aerodynamic performance, trim, and stability. Other design challenges include the nature and number of the design variab...

This paper investigates and characterizes the aerodynamic performance of a unique platform of airfoils with inflatable, elastomeric actuators. By controlling the inflation of stretchable and tough pneumatic bladders of silicone at specific locations of threedimensionally printed airfoils, experiments demonstrate it is possible to manipulate aerodynamic lift and drag. Measurements on morphable a...