In this paper experimental results on the near field of the flow past a sphere in a linearly stratified medium are presented. Emphasis is placed on the variation of the flow separation line with internal Froude number F=U/NR and also with Reynolds number Re=2RU/ν, where U and R are, respectively, the velocity and the radius of the sphere, N is the Brünt–Väisälä frequency (rad sec−1 ), and ν is the cinematic viscosity. It is shown that in the Reynolds number range 200<Re<30 000 the flow is primarily conditioned by the Froude number when F≤1. The condition F=1 defines a resonance state between the sphere and the internal wave field. In this case the waves create a strong depression behind the sphere that keeps the flow from separating. When F<0.8 the flow is two dimensional in a layer confined between the upper and the lower wave. When F>1.5 the flow starts to recover its three‐dimensionality.

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