Wave turbulence buildup in a vibrated plate

AULIEL MARIA INES; MORDANT NICOLAS

Tandil, Prov. de Buenos Aires

Congreso; XIII Reunion de Fluidos y sus Aplicaciones; 2014

CONICET - UNCPBA - CICPBA - UNCPBA - CLAF

Wave turbulence concerns the statistical state of a large number of nonlinear waves such as the sea surface of the various plasmas waves in a tokamak. The weak turbulence theory has been developed for these two examples in the 1960´s and generalized subsequently to almost all cases of nonlinear dispersive waves. Nevertheless there is very little numerical or experimental, data available due to the difficulties inherent in the study of weakly nonlinear waves. Indeed as for fluid turbulence, weak turbulence is characterized by wide ranges of length scales as well as the necessity to study the wave systems over very long times due to the slow nonlinear dynamics. In this respect,the study of weak turbulence are more challenging than that of fluid turbulence. Subsequent studies have shown that a vibrated plate supports weak turbulence, which is close to the phenomenology of the theory. The present work will be devoted to the study of directional spreading of energy in wave turbulence in a vibrated plate in the stationary case. The forcing of wave turbulence in experiments is often directional as it is the case in real systems. The observed spectrum is then anisotropic at almost all scales generated by non linear coupling of the waves. We study this anisotropic forcing and the subsequent return to isotropy (or lack there of) at smaller scales. We will implement high speed profilometry on surface waves on a vibrated thin steel plate. Although the stationary case seems to be consistent with the theory of elastic plates, at least in the phenomenology, the transient evolution of the spectral has almost never been investigated experimentally. Predictions have been made that the buildup of the wave spectrum should follow a self similar evolution in which a front propagates from large to small scales. We propose to investigate this transient evolution experimentallyin realistic plates. We report first experimental results of the buildup of the wave spectrum when starting the forcing in a real plate.