### ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

## 5aPA15. Simulation of wave propagation through an inhomogeneous turbulent
medium with the aid of an integral formulation.

**Hirobumi Kaneko
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*130C Olde Derby Rd., Norwood, MA 02062
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A propagation simulation algorithm is described whereby, at the beginning
of step n, the pressure associated with a progressive wave is specified as a
function of time and lateral position along a planar surface, x=x[sub n]. The
algorithm for step n yields the pressure as a function of time and lateral
position at x=x[sub n+1]. The basic mathematical formulation employs an
integral equation that predicts the waveforms at arbitrary positions to the
right of the first surface. The medium between the point and the surface,
x=x[sub n], is turbulent. The integral over the surface involves the Green's
function for a point source in the actual medium. Although the exact Green's
function is extremely difficult to compute, it is argued that a good
approximation for moderate step sizes, |x[sub n-1]-x[sub n]|, results if the
Green's function is taken to be that which results from a ray-acoustics
approximation. Moreover, because the first caustic for a point source Green's
function is not encountered for a distance considerably longer than the
distance between successive caustics for a nominally parallel group of rays
within a ray tube, the difficulties of explicitly taking caustics into account
is circumvented with this algorithm.