GRAY OCEAN
A ten-dollar engineering solution
Vortices shed by fluid flow past an object can create vibration in that object. This can be detrimental, or just annoying in many different applications. It is caused by Von Karman vortices.
In smoke stacks this vibration can cause structural failure in moderate winds. Oil rig mooring lines and sub sea piping can be set into a slow whipping motions that increase the stress on the pipe and therefore shorten their life span.
In the case of this Land Cruiser the forward rack beam produced a deafening whine making conversation impossible. Why the vibration?
The vibration is caused by the vortices pealing away from the object in the opposites direction each time. When a swirl or vortex peels off an object it produces a force on the object in the opposite direction that the vortex gravitates to. (This is why a curve ball curves.) At certain speeds the action of the vortex peeling off the object induces a vortex to then peel of the other side. This forces it one way, then the other. This alternating force is vibration. (Note, in the case of the baseball, the balls rotation causes the swirl to always peel of the same side.)
By wrapping shock cord around the tube, you �trip� the flow to always shed vortices the same way. So eliminate the alternating force and you will eliminate the vibration.
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