Abstract
We investigate sound wave propagation in a monatomic gas using a volume-based hydrodynamic model. In Dadzie et al. [Physica A 387, 6079 (2008)], a microscopic volume-based kinetic approach was proposed by analyzing molecular spatial distributions; this led to a set of hydrodynamic equations incorporating a mass-density diffusion component. Here we find that these new mass-density diffusive flux and volume terms mean that our hydrodynamic model, uniquely, reproduces sound wave phase speed and damping measurements with excellent agreement over the full range of Knudsen number. In the high Knudsen number (high frequency) regime, our volume-based model predictions agree with the plane standing waves observed in the experiments, which existing kinetic and continuum models have great difficulty in capturing. In that regime, our results indicate that the "sound waves" presumed in the experiments may be better thought of as "mass-density waves," rather than pressure waves.
Original language | English |
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Article number | 016103 |
Number of pages | 11 |
Journal | Physics of Fluids |
Volume | 22 |
Issue number | 1 |
DOIs | |
Publication status | Published - Jan 2010 |
Keywords / Materials (for Non-textual outputs)
- acoustic wave propagation
- density
- diffusion
- Knudsen flow
- Navier-Stokes equations
- rarefied gas dynamics
- kinetic theory
- extended hydrodynamics
- mass/volume diffusion
- diffusive transport