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Hi Jim,

A 60 mph wind is highly subsonic, which means that we can pretty much ignore any effects of compressibility, and use the (simpler) results for compressible fluids.

If all you were interested in was a tube of 1 m^{2} cross section
that narrowed down to 0.25 m^{2}, then it would be quite easy, and
the solution could be found in the fluid dynamics chapter of a text such as
Halliday, Resnick and Walker. For an inviscid, incompressible fluid in
steady state flow (nothing changing with time), conservation of mass
requires that Av=constant, where v is the fluid velocity and A is the cross-
sectional area of the tube. Bernoulli's equation (essentially conservation
of energy) gives us P + 0.5rv^{2}+rgy=constant, where P is the pressure, r is the fluid density, g is the acceleration of gravity, and
y is the height above some reference point. These two equations would tell
you how the fluid accelerates and the pressure decreases in the constricted
tube.

The problem which you're posing sounds more like a funnel embedded in what would otherwise be an infinite, uniform wind. That's a problem of the ilk encountered by aeronautical engineers. One of my colleagues with such a background suggested a couple of classic texts which may be of help to you. One is "Mechanics of Fluids," by Irving Shames, and the other is "Boundary Layer Theory," by Schlichting. The results will depend heavily upon the viscosity of the air and the length of the pipe, which will determine whether or not the boundary layers grow sufficiently to overlap and dominate the problem.

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