Point Vortex Flow Around a Cylinder

    Point vortex flow around a cylinder is given by the vector field
        Overscript[v, ⇀] = γ/(2π) (-y/(x^2 + y^2), x/(x^2 + y^2)) defined for (x^2 + y^2)^(1/2) ≥R
with parameter
        γ which represents the strength of the vortex.
    We can see the vector field with the following Mathematica commands

Needs["Graphics`PlotField`"] γ = 4 ; v[x_, y_] := If[x^2 + y^2& ... bsp;       (* Now we ensure that the result is shown *)


Changing γ simply dilates the resulting vectors.