Interaction of acoustic oscillations with time-dependent compressible convection

We present the results of numerical simulations in which acoustic waves are driven into a two-dimensional layer of compressible fluid which is undergoing convection. The energetics of the waves are analyzed by computing the work integrals associated with the modulation of the gas and turbulent pressures. We find that the relative importance of the turbulent pressure component of the work integral increases prominently with increasing wave frequency. Also, the time dependence of the convection leads to temporal irregularity in the component of wave driving and damping associated with the convection-pulsation coupling. We speculate that such irregularity may contribute to the aperiodicity observed in the light curves of Mira variables and other pulsating red giant stars.