Comments on “Propagation of Forced Sound Waves in Rarefied Gasdynamics” [L. Sirovich and J. K. Thurber, J. Acoust. Soc. Am. <b>37</b>, 329–339 (1965)]

Abstract

A recent paper of Sirovich and Thurber [J. Acoust. Soc. Am. 37, 329–339(1965)] presents comparisons of their theory with experiments. The comparison is inappropriate since the theory does not describe the experimental situation. Their theory is appropriate to free waves, propagating a distance that is large as compared with the mean free path between intermolecular collisions. The experimental data at low pressures have been determined by apparatus dimensions that are small as compared with that mean free path.