Discovery of a nonpropagating hydrodynamic soliton

A new type water-surface-wave soliton, nonpropagating hydrodynamic soliton, has been discovered. This is a self-trapped, highly localized and stationary transverse water-surface-wave excitation which appears in a rectangular cross section resonator continuously excited parametrically by vertical oscillation. An experiment designed to create the soliton and the features of the soliton are described. The profiles of the soliton for various frequencies and amplitudes are measured. It is found that the profile of the soliton is accurately given by a hyperbolic secant function. The stability region that is the amplitude and frequency range of the drive in which individual soliton can be created without hysteresis is experimentally determined. The interaction between two solitons has been investigated. It is observed that an attractive force exists between two solitons with the same polarity and a repulsive force exists between two solitons with the opposite polarity.