Wave turbulence theory of elastic plates

Abstract

This article presents the complete study of the long-time evolution of random waves of a vibrating thin elastic plate in the limit of small plate deformation so that modes of oscillations interact weakly. According to the wave turbulence theory a nonlinear wave system evolves in longtime creating a slow redistribution of the spectral energy from one mode to another. We derive step by step, following the method of cumulants expansion and multiscale asymptotic perturbations, the kinetic equation for the second order cumulants as well as the second and fourth order renormalization of the dispersion relation of the waves. We characterize the non-equilibrium evolution to an equilibrium wave spectrum, which happens to be the well known Rayleigh-Jeans distribution. Moreover we show the existence of an energy cascade, often called the Kolmogorov-Zakharov spectrum, which happens to be not simply a power law, but a logarithmic correction to the Rayleigh-Jeans distribution. We perform numerical simulations confirming these scenarii, namely the equilibrium relaxation for closed systems and the existence of an energy cascade wave spectrum. Both show a good agreement between theoretical predictions and numerics. We show also some other relevant features of vibrating elastic plates, such as the existence of a self-similar wave action inverse cascade which happens to blow-up in finite time. We discuss the mechanism of the wave breakdown phenomena in elastic plates as well as the limit of strong turbulence which arises as the thickness of the plate vanishes. Finally, we discuss the role of dissipation and the connection with experiments, and the generalization of the wave turbulence theory to elastic shells.

4-wave dynamics in kinetic wave turbulence

“…Furthermore, this approach allows us to identify and test the properties of the leading order equations of the 4-wave dynamics. As a matter of fact, the recent work [34] has demonstrated the agreement of part of our results with the kinetic equation in [42], that had been derived through asymptotic methods [41]. Reference [34] also shows the agreement of the predictions of the PDF equation with direct numerical simulations of relevant 4-wave systems.…”

“…Definition (54) implies that the delta's inside (53) also vanish in the term * 2...7 . Thus, a diagram for b (1) 1 implying the arguements of the delta's inside (41) to be simultaneously equal to zero is not contributing. The same holds for a graph for b…”

Elastic weak turbulence: From the vibrating plate to the drum

“…The mean value · represents an ensemble average and L is the size of the plate. Formally, the kinetic equation is given by (for a detailed derivation see [22])…”

“…Wave turbulence theory is based on a multi-scale perturbation expansion, in which the kinetic equation emerges as a condition to keep bounded the long time limit behavior of the expansion. The general formalism can be found in several works [40,42], in particular for elastic plates in [22]. The wave turbulence formalism requires the understanding of the long time behavior of the integrals…”

Strong turbulence for vibrating plates: Emergence of a Kolmogorov spectrum

“…When F = D = 0, Eqs. (1) and (2) derive from a Hamiltonian principle [13,30]. More importantly, it is a well-posed system, in the sense that the energy E = E kin + E stret is composed of two 064804-2 positive (hence bound from below) quantities, namely, the kinetic energy and the stretching energy per unit mass, yielding, respectively,…”