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Unformatted text preview: Lecture F18 Mud: Vortex, Lift (38 respondents) 1. What’s the difference between r and R ? (1 student) r is a general radius, as in r- κ polar coordinates. R is the specific cylinder’s radius. V 2. How can we define C as − / 2 ? (1 student) For a vortex defined by V = C/r , we calculate its circulation to be = − 2 C . So C and are effectively equivalent, since they differ only by the constant factor of − 2 . We can use them interchangeably. Since is more aerodynamically significant (directly related to vorticity, lift, etc.), we choose to use instead of C to define the vortex: = − / (2 r ). 3. I don’t understand . (1 student) I don’t know how to explain it better without just repeating the lecture material. Maybe try reading Anderson 2.13 again? One suggestion is to clearly distinguish the definition from the implications. Two equivalent definitions are θ n dA − V · dθs or − θ · ˆ Some implications are: = for any circuit in irrotational ﬂow not enclosing a body.body....
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This note was uploaded on 01/28/2012 for the course AERO 16.01 taught by Professor Markdrela during the Fall '05 term at MIT.
- Fall '05