Rotating Jet

This photo, one of the winners of the Engineering and Physical Sciences Research Council’s (EPSRC) annual photography contest, shows a rotating viscoelastic jet. Rotating liquid jets are common to many manufacturing processes, and their sometimes-wild appearance comes from a balance of gravitational forces and centrifugal force against surface tension. But because this fluid contains a small amount of polymer additive, surface tension has the additional aid of some elasticity to help hold the jet together and keep the globules and ligaments you see from flying off. As centrifugal forces fling the fluid outward, it stretches the polymer chains within the fluid, and they pull back against that tension like a stretched rubber band. To see some of the other contest winners–including other fluids entries!–check out the Guardian’s run-down. (Image credit and submission: O. Matar et al., ICL press release)

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