H. Arbell and J. Fineberg
Institute of Physics, The Hebrew
Received 18 January 2000; revised 29 March 2000
Stationary, highly localized (oscillon) structures are observed in a Newtonian fluid when nonlinear surface waves are parametrically excited with two frequencies. Oscillons have a characteristic structure, that of periodically self-focusing jets. In contrast to previously observed oscillons in highly non-Newtonian media, these states are temporally harmonic with the forcing. For wave amplitudes greater than a critical value, they nucleate from an initial pattern via a hysteretic bifurcation, and can therefore be localized on a background of patterns with a variety of different spatial symmetries.