We have used an electronic technique [J. Pierrus and O. L. de Lange, Phys. Rev. E 56, 2841 (1997)] to monitor damped oscillations in Rüchardt’s experiment for twelve gases (He, Ne, Ar, Kr, Xe, ${\mathrm{N}}_2,$ ${\mathrm{CO}}_2,$ ${\mathrm{N}}_2\mathrm{O},$ ${\mathrm{CHF}}_3,$ ${\mathrm{CCl}}_2{\mathrm{F}}_2,$ ${\mathrm{SF}}_6,$ and ${\mathrm{C}}_2{\mathrm{ClF}}_5$) at room temperature and pressure. The nature of the oscillations depends on frequency (volume of gas) and amplitude. The bulk modulus $K$ and relaxation time τ are measured over a range of volumes of gas (0.12–23 l: frequencies ∼8–0.5 Hz) and amplitudes (6–0.01 cm). In gases for which $C_p{/C}_v$ is not too low, there is evidence for an initial, transient adiabatic oscillation lasting one or two cycles. This is followed by a set of intermediate oscillations, which is observed for all gases, and can be studied in detail. For these oscillations, the agreement between experiment and theory is good. In particular, gases such as He and Ne exhibit high damping, whereas gases such as ${\mathrm{SF}}_6$ and ${\mathrm{C}}_2{\mathrm{ClF}}_5$ have low damping, as predicted by theory. The intermediate oscillations are followed (as the amplitude decreases) by a second set of oscillations of constant, longer period. For the monatomic and diatomic gases the values of $K$ and τ for these oscillations are consistent with isothermal oscillations, although the measurements of τ indicate the presence of residual thermal gradients at the higher frequencies (smaller volumes). For the polyatomic gases, measurements of τ yield a similar conclusion; however, values of $K$ are lower than theoretical values for isothermal oscillations, and the disparity increases with the polyatomicity of the gas. In all gases, the amplitudes of oscillations in the isothermal tail increase as the frequency is decreased.

• Received 23 December 1997

DOI:https://doi.org/10.1103/PhysRevE.57.5520