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126 3. Further applications
This, and other aspects of compressible flow past aerofoils, will be put to one side in
the current discussion (but some additional ideas are addressed in Q3.10 and 3.11).
Here, we will work with the mathematical model for the flow in which and
are bounded, so that the only non-uniformity arises as
The solution in the far-field is written in terms of the variables and
with Equation
(3.22) now becomes
where, for simplicity, we have written down only the leading terms on the right-hand
side of the equation. We seek a solution
and then satisfies the nonlinear equation
or
and note that The general solution for is
where H is an arbitrary function; solution (3.39) provides, for general H, an im-
plicit representation only for (which has far-reaching consequences, as we shall see
shortly).
We determine H by matching, and this is most easily done by matching and
—but for this we require the expansion of It is left as an exercise to show that,
from (3.35), we obtain
which gives