Flow in a Closed Channel

    The flow inside the closed channel of width w given by y≥0, -w/2≤x≤w/2 is given by
        Overscript[v, ⇀] = U (cos ((π x)/w) cosh ((π y)/w), sin ((π x)/w) sinh ((π y)/w))
with the parameters
        U - scaling factor for the velocity,
        w - width of the obstacle.

Needs["Graphics`PlotField`"] U = 1/100 ; w = 1 ; v[x_, y_] := If[x≥ -w/2 & ...                                                                             2                   2


    Changing either U or w results in a simple re-scaling of the problem.