### ASA 126th Meeting Denver 1993 October 4-8

## 2aPAb11. Coupled wave equations for numerical calculation of acoustical
propagation and scattering by atmospheric turbulence.

**Michael De Antonio
George H. Goedecke
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*Dept. of Phys., NMSU, Las Cruces, NM 88003-0001
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**Harry J. Auvermann
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*Army Res. Lab., Battlefield Environment Directorate, WSMR, NM 88003-5501
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The usual approximate acoustic wave equations [e.g., A. D. Pierce, J.
Acoust. Soc. Am. 87, 2292 (1990)] were developed for ambient conditions
(turbulence) in which the scale length a of the spatial variation of
temperature and flow velocity is much larger than the acoustical wavelength
(lambda); this is not the case in many applications of interest. An alternative
set of coupled acoustical wave equations, valid for any a/(lambda), is
presented. These equations involve no approximations except the usual neglect
of the viscosity terms in the Navier--Stokes equation for the acoustic flow.
For quasistatic or ``frozen'' turbulence, the integral forms of these equations
are presented, suitable for application of the digitized Green's function
method [G. H. Goedecke and Sean G. O'Brien, Appl. Opt. 27, 2431 (1988)].