AN ULTRASONIC BACKSCATTERING FROM THE WAK E PAST A CYLINDER IN A CONTINUOUSLY STRATIFIED LIQUID

A wake past a circular cylinder in a continuously stratified water was observed by optical technique and simultaneously sounded by laborator y echo-sounder (frequency 1 MHz) which was connected to an IBM compute r. The facility provided and information rate about 1.2 x 10(6) bit/s. The shadow pictures of flow and synchronous vertical profiles of scat tered signals were obtained. A time dependence of backscattering shows three stages concerning the flow regime (the regime is characterized by the Froude number 0.46 and Reynolds number 322): large-scale moveme nt, internal wave generation and decay of three-dimensional flow. As t ime progresses, a tendency was observed of displacement of scattered s ignals maximums to the boundaries of the flow.