Movement of a solid within a fluid
The study of the movement of a solid within a fluid has a great practical interest, from the design of the aircraft to the effect that gives the ball a soccer player.
Suppose a symmetrical body as a cylinder, as we see in the figure, the current lines are distributed symmetrically. The velocity of the fluid is zero at the ends of its horizontal and maximum diameter at the ends of its vertical diameter, passing through intermediate values for diameters having a different orientation.
If the fluid is ideal, the pressures are distributed symmetrically around the body so that the forces due to pressure cancel each other at the ends of each diameter. The resultant of the forces exerted by the fluid on the body is zero. Thus, the paradox will arise that a symmetrical body is not drawn when placed within a stream of a perfect fluid.
What is the Magnus effect?
The Magnus effect explains why the spinning motion of a solid determines its path within a fluid.
This effect was observed by Thomas Edison but it was not until the German physicist and chemist Heinrich Gustav Magnus studied it a few years later that the reason for its consequences was known. In honor to this scientist baptized to this phenomenon Magnus Effect.
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Source: 1) https://www.parabola.unsw.edu.au/files/articles/1990-1999/volume-33-1997/issue-1/vol33_no1_1.pdf
3) http://www.iflscience.com/physics/spinning-basketball-drops-and-swerves-away-due-magnus-effect/
Video credits: Roger Linsell
