Description:
Numerical simulations of the Navier-Stokes equations modeling the propagation and reflection of acoustic waves generated by wall heating within closed cavities can only adequately capture the pre- dicted experimental trends when soft walls are considered instead of hard ones. In other words, wall impedance must be included in the model to take into account wave amplitude (resistance) and phase (reactance) losses upon reflection at the wall. Such hydrodynamic model simulations, however, are usually restricted to one-dimensional scenarios due to stiffness, since the extreme disparity between the smallest (acoustic) and largest (thermal diffusion) time scales lead to very large CPU times. Hence, the acoustic scales are often filtered out and their effect is modeled instead. Known as thermodynamic models, they require much smaller CPU times. The present paper shows for the first time how soft wall resistance effects can be included in a thermodynamic model, leading to a significant improvement in their ability to predict experimental trends while still requiring low CPU times. It also allows the discovery that soft wall resistance turns the piston effect negligible even near criticality