The effect of memory in behaviour of vials of air under water is found out

Openly new phenomenon in hydrodynamics: effect of memory of the form at a separation from a surface of vials of air under water. The hydrodynamic currents movable by forces, but possessing memory, meet to physicists for the first time.

The drops of the water filtering through badly closed crane, turn out round without dependence from, whether there was an exhaust outlet round, triangular or had any more difficult form. It it is no wonder as the superficial tension and viscosity just aspire to transform any initial form into the round. It is possible to tell that under the influence of these forces water "forgets" the initial condition.

In the course of drop formation there is, however, one intriguing stage which details are not up to the end studied till now. Some instants prior to a drop separation its great bulk already moves downwards by gravity, and to an initial surface it is connected by only narrow isthmus.

At approach by the time of a separation this isthmus is extended and decreases till the nuclear sizes and at last is torn. A Fig. 2. A vial separation at slightly inclined exhaust outlet: the front view and sideways. Even weak infringement of symmetry affects the isthmus form (the image from article Phys. Rev. Lett. 97, 144503)


Theoretical calculations foretold that process of reduction of an isthmus too is characterised by loss of memory of the initial form. Not important, what exhaust outlet was: the isthmus quickly accepted not the symmetric form. Developed last decades the last century the technology of a superfast video shooting (with frequency over 100 thousand shots a second) has confirmed in general correctness of this conclusion.