Physics of a toy geyser
  A geyser can be reproduced by a toy experiment composed of a water pool located above a water reservoir, the two being connected by a long and narrow tube. When the bottom reservoir is heated, the system experiences periodic eruptions of hot water and steam at the top similarly to the geyser effect occurring in nature. The eruption frequency of a toy geyser is inspected experimentally as a function of the heating power and the height of the set-up. We propose a thermodynamic model of this system which predicts the time between eruptions. Besides, the geometric and thermodynamic conditions required to observe a geyser effect are discussed. The study of the toy geyser is then extended to the case of two reservoirs connected to the same tube. In such a configuration, an eruption in a reservoir may entrain the eruption of the other. Such a coupled system adopts a complex time-evolution which reflects the dynamics of natural geysers. We analyze the behavior of a toy geyser with two reservoirs by the way of statistical tools and develop a theoretical model in order to rationalize our observations. 
Martin Brandenbourger, St\'ephane Dorbolo, Baptiste Darbois Texier
physics.flu-dyn physics.geo-ph