VORTEX SYSTEMS PAST A CYLINDER IN A CONTI NUOUSLY STRATIFIED FLUID

A fine structure of linearly stratified fluid past a rigid circular cy linder towing with constant speed is investigated by schlieren and dye -streak visualization. The influence of scaling parameters on the flow structure is studied in a wide range of their values: 5 < Re = Ud/nu < 1400, 0.001 < Fr(i) = U/Nd < 3(0.01 < U < 3 cm/s, 0.2 < N < 1 s-1, 0 .8 < d < 7.6 cm) 14 different flow structure types are identified in a transient regime. A new type of instability is revealed leading to so -called structural turbulence when a random density field is accompani ed by a slowly varying velocity field. Given classification of basic f low forms is based on linear scales describing basic and secondary flo w patterns.