Intensity fluctuations of ultrasonic scattering in a highly turbulent flow

Aspects of ultrasound intensity fluctuations backscattered from additive mi crostructures in a turbulent flow have been investigated theoretically and experimentally for the conditions of a small insonified volume, a high soun d frequency and strong turbulence. These conditions are typically found in high resolution Doppler sonar applications. An easily applicable expression for the auto-correlation of scattering intensity fluctuations is obtained by introducing open-channel turbulence theory, a semi-empirical scalar spec trum (including a Batchelor spectrum) and a Gaussian window function. Exper iments carried out in a laboratory-clear water, open-channel flow for diffe rent turbulence levels verify the underlying assumptions. A good agreement is found with the predictions made with the above-derived expression. The f easibility of extracting flow information from the backscattered intensity fluctuations is discussed. (C) 2000 Elsevier Science B.V. All rights reserv ed.