Visualization and Echo Sounding of Stratified Fluid Disturbances in Front of and Behind a Vertical Plate

With the use of the schlieren visualization and echo sounding method, the spatial structure of disturbances in front of a plate and behind it is investigated for the first time in the flow regime of intense internal-wave generation. In the echograms, fine structures are detected both in the upstream disturbances and in the wake within the solid-motion layer. In the schlieren graph, the fields of upstream disturbances are smooth, and thin interfaces are expressed in the confluent wake. Local peaks in the spatial disturbance spectra are expressed on scales that slightly exceed the length of internal waves, and, to a lesser extent, for lower scales. The thinnest interfaces are observed in the schlieren image of the wake immediately behind the plate.