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The Hygrocyst–a Stability Phenomenon in Continuum Mechanics


CONSIDER a long sealed container partially filled with a liquid or completely filled with two immiscible liquids and oriented horizontally. If the container is rotated about a horizontal axis, a laminar secondary flow pattern develops that is characterized by large regular regions of segregated material. The onset of this new flow pattern appears to be the result of a natural instability in the normal flow, and is found to occur in containers of all geometries. The flow instability and the associated laminar secondary flow pattern discussed here are, to my knowledge, being reported and studied for the first time and do not appear anywhere in the published scientific literature. This might seem surprising at first in view of the apparent simplicity of the phenomenon, but when it is viewed in terms of its mathematics, with its difficult boundary conditions and unusual body force orientation, it becomes understandable why it would be unlikely that anyone could predict its existence from mathematical considerations alone. Further, it is rather difficult to demonstrate the instability by experiment with inelastic fluids.

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BALMER, R. The Hygrocyst–a Stability Phenomenon in Continuum Mechanics. Nature 227, 600–601 (1970).

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