Pipe effect in viscous liquids
  A detailed experimental and theoretical study has been performed about a phenomenon, not previously reported in the literature, occurring in highly viscous liquids: the formation of a definite pipe structure induced by the passage of a heavy body, this structure lasting for quite a long time. A very rich phenomenology (including mechanical, optical and structural effects) associated with the formation of the pipe has been observed in different liquids. Actually, the peculiar dynamical evolution of that structure does not appear as a trivial manifestation of standard relaxation or spurious effects. In particular we have revealed different time scales during the evolution of the pipe and a non-monotonous decreasing of the persistence time with decreasing viscosity (with the appearance of at least two different maxima). A microscopic model consistent with the experimental data, where the pipe behaves as a cylindrical dielectric shell, has been proposed. The general time evolution of the structure has been described in terms of a simple thermodynamical model, predicting several peculiarities effectively observed. 
V. Capano, S. Esposito and G. Salesi