Molecular simulation of sound for development of nanoacoustics

Takeru Yano

Large scale molecular dynamics simulations have been performed to clarify the nonlinear and non-equilibrium processes of high-frequency sound waves in a gas. Since the number density of molecules in a gas is considerably small compared with those in liquids and the wavelengths of sound are very large compared with molecular scales even for high-frequency (gigahertz) sound, we put more than 0.3 million molecules in a simulation box with the length of several micrometers in the direction of wave propagation. The one-dimensional sound wave is generated by a harmonic oscillation of sound source with the Lennard-Jones intermolecular potential, which is the same as that of gas molecules. As a result, we find that the large amplitude and high-frequency sound propagates with strong attenuation, in some cases, exhibiting a stream-like profile accompanied with mass, momentum, and energy transports. This leads to a completely different picture and a different dispersion relation from a classical theory of high-frequency sound based on the linear standing wave analysis.

Mots clés: molecular dynamics; Lennard-Jones gas; Numerical simulation; Non-linear acoustics

Domaines: Acoustique [physics.class-ph]

Takeru Yano. Molecular simulation of sound for development of nanoacoustics. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811370⟩