4aPA11. Acoustic sensing of the nonlinear dynamics of density stratified vortices.

Session: Thursday Morning, May 16

Time: 10:45

Author: Alexander B. Ezersky
Author: Poul L. Soustov
Author: Alexander B. Zobnin
Location: Inst. of Appl. Phys., Russian Acad. Sci., 46 Ulyanov str., Nizhny Novgorod 603600, Russia


Data on the nonlinear processes in an atmosphere and in the ocean may be obtained by means of remote acoustic sensing. The principal task is to use the data obtained in experiments for reconstruction of temperature, pressure, and velocity fields, and thus reconstruct the flow. Results of laboratory investigations of the potentialities of remote acoustic sensing of flows are presented. The scattering of sound at vortices behind a cylinder was explored. The temperature of the cores of the vortices formed as a boundary layer was detached from the heated cylinder was higher than that of the incident flow. The experiment was performed in a low-turbulence wind tunnel at flow velocities much lower than the sound velocity. It is shown that the characteristics of the scattered signal (indications of scattering and time spectra) may be used to determine vortex parameters such as vorticity, repetition rate, and spatial period, to estimate the temperature of vortex cores and the amount of the heat transferred, as well as to identify the processes of vortex merging and vortex core oscillations. Results of acoustic sensing are in a good agreement with theoretical estimates, direct measurements by a hot-wire anemometer, and data of experiments on vortex visualization.

from ASA 131st Meeting, Indianapolis, May 1996