Dynamics of liquid-air interface following vertical acceleration-deceleration motion

We investigated the behavior of the liquid-air interface in a test tube that is displaced by a downward impulsive force. By using both experimental and numerical approaches, we observed the formation of a singular jet when the contact angle between the liquid and the tube wall is larger than 90 degrees. The jet height calculated from the numerical simulations is validated against the experimental results. The characteristics of the jet is mainly determined by the Weber number (We), Reynolds number (Re), and the initial shape of the interface. For the same initial interface shape, a Re-We phase diagram for no breakup, Rayleigh jet breakup and splash regime is obtained. The contact angle affects the initial shape of the interface, and thus modifies the phase diagram. The jet height dependence on the Weber number is also studied.