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This is actually not a completely settled question, so don't feel too bad if you don't understand it in every detail! It's also possible that the cause is not the same in all situations, and be aware that my explanation is not universally accepted, but here's my interpretation: There are actually two interacting phenomena going on: the formation of the ...


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So the vortex street appears as the stream goes faster and faster: the stream obeys Newton's laws, "objects in motion tend to stay in motion unless acted on by a net force." The force that keeps the stream laminar around the cylinder is fluid pressure formed by the viscous forces of the fluid, which means there is a pressure gradient and a region of low ...


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I would use the traditional drag equation: F = 0.5 * p * v^2 * Cd * A Reasoning: Stokes' law is for very small Reynolds number flows only (much less that 1), and I don't believe the more common drag model has any such restriction. The problem is that you will need to know the drag coefficient of the ball in question to use this force model. Sources: I ...


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Depends on the Reynolds number. Stokes can be used for purely laminar flow. Complete answer to be found here.


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If u want to find exit pressure of control volume you have consider, you can use Bernoulli equation since you know exit velocity profile. Since boundary layer is thin and no flow separation, this flow is more or less irrotaional flow and I'm assuming the flow is steady. $$ p_1 +\rho \frac{v_1^2}{2} =p_2 +\rho \frac{v_2^2}{2}$$ Here $p_1$, $v_1$ are inlet ...


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It has to do with size. For small and slow-moving objects, viscous forces have more weight in comparison to inertial forces. Also, the layer of air close to the surface of an object which moves through air is differently structured. The dimples in a golf ball will make this layer resemble that of larger objects and help to make the flow resemble that around ...


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Mythbusters covered this one. They found significant fuel saving at constant speed. Assuming their findings are correct I can only guess that the technique is not used for cosmetic reasons ie few people would want to drive a car that looks like it has been in multiple accidents and covered in dents


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Major classes of drag:Two main factors of drag are friction and flow separation. This friction drag is dominant in streamlined shape and pressure drag (drag due to flow separation) is dominant in bluff body. Ways to reduce friction and pressure drag: Turbulent flow has more momentum than laminar flow so they reduces flow separation so pressure drag is ...



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