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Flow around a two-dimensional circular cylinder of a stratified fluid with periods buoyancy T = 25.2 and 6.28 sec is studied numerically over a wide range of Reynolds and Froude numbers. It is found that in the presence of a perturbation ahead of a cylinder which moves downstream with increasing Reynolds number, the salinity isolines have the shape of a semi-circular comb with sharp teeth. The shape change of the attached waves and the occurrence of fluid layers of different densities in the cylinder wake are studied. In flows with a buoyancy period T = 6.28 sec at Reynolds numbers Re < 60, stagnant zones are found in the cylinder wake, and at Re > 60, these zones are absent. [ABSTRACT FROM AUTHOR]

The fine structure of the flow field of a continuously stratified fluid around a circular cylinder for small values of the Froude number was investigated in laboratory and numerical experiments. The parameters of the leading perturbation, the internal-wave field, and the cylinder wake were calculated using a two-dimensional model. The existence of the previously experimentally observed high-gradient density layers in the wake that are parallel to the flow axis was for the first time confirmed by numerical calculations. Results of the numerical and experimental studies are in good agreement with each other and with analytical models for small values of the Froude number. [ABSTRACT FROM AUTHOR]