Poster 17

Matthew Thrasher UT-Physics

The Bouncing Jet A viscous liquid stream plunging toward a horizontally moving bath of the same liquid can bounce off the surface without mixing with the bath’s fluid. A thin layer of air separates the jet and the bath. The non-coalescing jet ramps off an indentation that it makes in the bath’s surface. The jet then moves in a roughly parabolic flight until it hits the translating surface again, where it may bounce a second time. Similar rebounding phenomena, such as the Kaye effect, have been observed in non-Newtonian fluids. However, we report the first observations of a bouncing Newtonian liquid jet. The bouncing jet involves an interplay of viscous, inertial, surface, and gravitational forces. We observe the bouncing jet for many different liquids, including silicone oil. The bouncing jet is stable for a large range of parameters, including the oil’s viscosity (50 to 520 mPa s), the jet’s radius (0.05 to 0.12 cm), the jet’s velocity at impact (40 to 170 cm/s, corresponding to nozzle heights 1.7 to 14 cm), and the bath’s horizontal velocity (1 to 35 cm/s).