Radial and tangential velocities for Inviscid flow (fluid mechanics)

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In fluid mechanics, when analyzing flow past a cylinder, the radial velocity component must be zero at the surface because flow cannot penetrate the solid surface. However, the tangential velocity component does not need to be zero at the surface in inviscid flow conditions. Stagnation points, located at the leading and trailing edges of the cylinder, exhibit both radial and tangential velocities of zero. Understanding these conditions is crucial for solving problems involving stream-functions and velocity components. This clarification enhances the comprehension of flow behavior around cylindrical objects.
wahaj
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After I have an expression for the stream-function in a problem, I can differentiate to get the tangential and radial velocities because I need those to solve the problem. But I don't understand when the tangential velocity will be 0 and when the radial is 0. Can some on explain?
 
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wahaj said:
After I have an expression for the stream-function in a problem, I can differentiate to get the tangential and radial velocities because I need those to solve the problem. But I don't understand when the tangential velocity will be 0 and when the radial is 0. Can some on explain?

Is this for flow past a cylinder or past a sphere?

Chet
 
I didn't realize there was a difference but cylinders for this question.
 
If you're referring to the radial and tangential velocity components at the surface of the cylinder, then the radial component has to be zero, since you can't have flow through the solid surface of the cylinder. For inviscid flow, the tangential component of the velocity does not have to be zero at a solid surface. The leading edge and the trailing edge of the cylinder are both stagnation points, so both components of velocity are zero at these points.

Chet
 
Thanks for clearing this up.
 

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