In this section an implementation of the Rayleigh Integral
Method is described. The plate may be of any shape and is assumed
to be discretised into a set of planar triangles.
The normal velocity distribution on the plate is described
simply by its value at the centroids of the triangles,
the interpolation points. The basis functions
c1, c2, ..., cn
are the constant functions; cj,
taking the value of unity on the jth panel and
zero on the remainder of the plate.
The points p1, p2,
... pn are the centroids of the triangular elements;
{ Lk cj }[(P)\tilde] = { Lk e }D[(P)\tilde]j
where e is the unit function e(p) = 1.
As input, the subroutine accepts a description of the geometry of the
plate (made up of triangles), the coordinates of selected points in the
exterior (where the sound pressure is required), the wavenumbers under
consideration and a description of the boundary condition
at each wavenumber. As output, the subroutine gives, for each wavenumber,
the acoustic intensity at the vertices of the triangles that make up the
approximate plate, the sound power, the radiation ratio and the sound
pressure at the prescribed exterior points.