Application of partial derivatives

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sorry folks i don't even have an idea to this question`s solution so i hope u people may like to help me. i`m stuck to it since last week nd i hope its from partial derivative... please suggest me a book or a hint or the solution.

Let a long circular cylinder of unit radius be placed in a large body of fluid flowing with uniform velocity, the axis of cylinder being perpendicular to the direction of flow. determine the steady flow.also show that the speed of the fluid at points on the cylinder surface is 2A|SinØ|.
 
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I would say your formula you are given is that the radius of the cylinder is say x2 + y2 = 1 (as it is a unit radius), and allow your function f(x,y) = x2 +y2 -1 = some constant C (as your Z value can be any value you want it to be as the cylinder extends in either direction of Z). So given this, you can solve for your gradient (which is the vector given by the partial derivatives). So partial f respect to x = 2x, partial f respect to y = 2y, so the gradient is given by the vector <2x,2y>. This vector would be equivalent to your uniform velocity vector (flow rate). After that I'm not really sure how to determine the exact velocity though.. that may start you?
 
i`ll try though i have only 1 day left to solve it... thank you for the reply...
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...
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