### ASA 125th Meeting Ottawa 1993 May

## 4pAO10. Use of the vector Bragg wave-number scattering condition to
measure turbulence.

**Louis Goodman
**

**
Diane Sargowicz
**

**
**
*Naval Undersea Warfare Ctr., Newport, RI 02841
*

*
*
**John Oeschger
**

**
Steven Letcher
**

**
**
*Univ. of Rhode Island, Kingston, RI 02881
*

*
*
**Peter Hebda
**

**
**
*Americom Corp.
*

*
*
Acoustic scattering that satisfies the far-field Born approximation leads
to a simple linear relationship between the scattered pressure field and the
scattering field, namely the two are Fourier transform pairs. A set of
laboratory experiments have been devised to exploit this relationship for the
case of scattering from a turbulent field. Data are taken in a multiple
scattering angle configuration such that the Bragg wave-number vector
associated with each scattering angle pair is in the same direction. Use of
broad bandwidth source and receiver transducers (250 to 750 kHz) then allows a
three-dimensional fully resolved wave-number spectra of the turbulent field to
be estimated. Results are presented for scattering from a turbulent buoyant
plume. The data can also be used to examine the validity of the fundamental
assumption of the far-field Born approximation.