-- In collaboration with Sophie Goujon-Durand --
A spherical obstacle in rotational motion is in the path of a liquid that flows from right to left. In order to better visualize the movements of the fluid particles, a dye is injected upstream of the orbicular obstruction. The jet goes around the spinning obstacle as best as it can but does not come out unscathed. The flow immediately behind the rounded dam is destabilized and takes the form of a helix, seen in this image as an oscillating and delicate brushstroke.
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