The cylinder that first encounters the fluid always experience more drag compared to its follower. This effect is so robust never a surprise that its conclusion was applied by many people when then dealt with shape-changing objects.
To an extreme, it is the common wisdom that birds in a flock and fish in a school also share the same drag allotments: it is more difficult to lead in a group than to follow. However, so far there is no direct experiment that has been down with such systems. To be more specific, there has been not a single experiment that measures the drag or the relative energy cost on a leading fish or bird in a group.
It does not mean that we have no way to tackle this problem. Instead of working with actively locomoting animals, we turn our attention to their passive counterparts: flapping flags that mimic the flapping motion of the swimming fish.
Here, flags are regarded as paralyzed fish that flap due to the interaction between its inertia and the surrounding fluid. In particular, our experiment examines the fluid drag acting on a pair of tandem flags that are flapping in a fast moving fluid. We used a simple custom-designed force gauge that is similar to the one used by Cavendish as he measured the gravitational attraction between heavy masses.
The reason, the drag force acting on a small object due to the flow of a thin soap film is very low, typically on the order of a few dynes, which is a quarter of the weight of a grain of rice.
As the drag acts in opposite direction of motion, the body that moves in the fluid has low pressure region in its rear end. Hence by making the selected body to move behind another body, we can reduce the drag force acting on the selected body. This method of reducing drag is known as drafting.
As drafting involves in making the body to move in low pressure region, the coefficient of drag of a drafted body is reduced to large extent. Search for:. Questions Members 0 health x 3 Growth x 2 security x 2 black x 2 tea x 2 beneifts x 2 coffee x 2 healthy x 2 benefits x 2 Nonconstant x 1 fixed x 1 income x 1 cash x 1 financial x 1 market x 1 solution x 1 manual x 1 Cholesterol x 1 free x 1 answer x 1 categories x 1 driving-tips x 1 driving x 1 tips x 1 Alabama road test x 1 alabama road test guide x 1 copart x 1 car x 1 inspector x 1 birmingham x 1 alabama x 1 See more tags TOP USERS.
What is drafting? Answer: Drag is the force which a flowing fluid exerts on a body in the flow direction. The difference between the pressure acting on the front surface of a body moving through a fluid and the pressure acting on its rear surface.
Form drag of an asymmetrical body depends on its orientation to the direction of free fluid flow. It increases with the cross-sectional area of the body aligned perpendicular to the flow. It is also affected by the shape and smoothness of the body; streamlining helps to minimize form drag.
Cyclists and, to a lesser extent runners, reduce form drag by following closely behind another participant a process called drafting.
Subjects: Medicine and health — Clinical Medicine. View all related items in Oxford Reference ». Search for: 'form drag' in Oxford Reference ». All Rights Reserved.
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