Molecular-dynamics simulation of thermoelastic waves in a solid induced bya strong impulse energy - art. no. 014302

A molecular-dynamics investigation of thermoelastic waves in a solid at var ious pressures and temperatures has been studied. The numerical experiments were performed on a two-dimensional (111) plane consisting of fee lattice particles having the Lennard-Jones (12-6) interaction potentials. Three typ es of impulse energy, including thermal, kinetic, and superposition of ther mal and kinetic energies, were employed to investigate the origins and char acteristics of the generated waves. According to their propagating speeds, three waves, namely, W-1, W-2, and W-3, were observed if a kinetic impulse energy was imposed. But only the W-1 and W-3 waves were detectable if the a pplied energy was thermal. The W-1 wave, accompanied by a strong compressiv e stress wave, is the first sound wave and caused by sudden expansion as th e impulse energy applied. Due to coupling of thermal and elastic energies, it is a nonequilibrium thermoelastic wave. The W-2 wave was initiated by st rong velocity disturbance in the longitudinal direction. If induced by a th ermal impulse energy, the W-3 wave is the so-called second sound. The monot onically decreasing of the second sound speed with increasing temperature i s also verified.