Sphere oscillating in a rarefied gas

Yap, Ying Wan; Sader, John E.

doi:10.1017/jfm.2016.143

Cited by 23 publications

(21 citation statements)

References 47 publications

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“…Apart from the fundamental interest in such studies, these investigations should shed light on the propagation of acoustic waves in a variety of practical micromechanical setups, where small length-and time-scales are encountered. Toward this end, Yap and Sader [16] have examined the acoustic field induced by a rigid sphere oscillating in a rarefied gas. Somewhat earlier, Kalempa and Sharipov [17] have investigated the thermoacoustic wave generation by the unsteady heating of a cylinder in a coaxial-cylinders setup.…”

Section: Introductionmentioning

confidence: 99%

Acoustic field of a pulsating cylinder in a rarefied gas: Thermoviscous and curvature effects

Ben-Ami

Manela

2017

Phys. Rev. Fluids

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We study the acoustic field of a circular cylinder immersed in a rarefied gas and subject to harmonic small-amplitude normal-to-wall displacement and heat-flux excitations. The problem is analyzed in the entire range of gas rarefaction rates and excitation frequencies, considering both single cylinder and coaxial cylinders setups. Numerical calculations are carried out via the direct simulation Monte Carlo method, applying a noniterative algorithm to impose the boundary heat-flux condition. Analytical predictions are obtained in the limits of ballistic-and continuum-flow conditions. Comparing with a reference inviscid continuum solution, the results illustrate the specific impacts of gas rarefaction and boundary curvature on the acoustic source efficiency. Inspecting the far-field properties of the generated disturbance, the continuum-limit solution exhibits an exponential decay of the signal with the distance from the source, reflecting thermoviscous effects, and accompanied by an inverse square-root decay, characteristic of the inviscid problem. Stronger attenuation is observed in the ballistic limit, where boundary curvature results in "geometric reduction" of the molecular layer affected by the source, and the signal vanishes at a distance of few acoustic wavelengths from the cylinder. The combined effects of mechanical and thermal excitations are studied to seek for optimal conditions to monitor the vibroacoustic signal. The impact of boundary curvature becomes significant in the ballistic-flow regime, where the optimal heat-flux amplitude required for sound reduction decreases with the distance from the source and is essentially a function of the acoustic-wavelength-scaled distance only.

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Section: Introductionmentioning

confidence: 99%

Acoustic field of a pulsating cylinder in a rarefied gas: Thermoviscous and curvature effects

Ben-Ami

Manela

2017

Phys. Rev. Fluids

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“…In the past decade, oscillatory gas flows have been extensively studied [11][12][13][14][15][16][17][18][19][20], most of which, however, are for flows between two parallel plates. While the viscous damping is dominate at low oscillation frequencies, at relatively high oscillation frequencies, inertial force leads to the interference of sound waves along the oscillating direction of the plate, so that the magnitude of the damping force on the oscillating plate oscillates when the oscillation frequency varies [18].…”

Section: Introductionmentioning

confidence: 99%

Sound propagation through a rarefied gas in rectangular channels

2016

Phys. Rev. E

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This version is available at https://strathprints.strath.ac.uk/58309/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output.Sound propagation through a rarefied gas in rectangular channels A sound propagation through a rarefied gas inside a two-dimensional cavity is investigated on the basis of the linearized Boltzmann equation, where one of the cavity wall oscillates harmonically in the normal direction to its own surface and is considered as a sound source. An analytical solution at high oscillation frequencies is obtained, and detailed numerical results for a wide range of gas rarefaction are presented. The influence of both the aspect ratio of the cavity and the oscillation frequency on the average gas pressure exerted on the oscillating plate is studied. It is found that, at large values of the aspect ratio, the average pressure oscillates when the sound frequency varies, due to the sound resonance and anti-resonance along the oscillation direction of the plate. However, at small values of the aspect ratio, the average pressure is a monotonically decreasing function of the sound frequency, which cannot be observed in the corresponding one-dimensional counterpart. This is explained by the sound interference in the direction parallel to the oscillating plate. The influence of both the cavity aspect ratio and oscillation frequency on the sound speed is also investigated: again it is found that different aspect ratio leads to the different behavior of the sound speed as a function of the oscillation frequency.

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“…The present problem is expected to provide fundamental information on the unsteady behaviour of rarefied gas if combined with recent results focusing on oscillatory shear-driven flows (e.g. Park, Bahukudumbi & Beskok 2004; Hadjiconstantinou 2005; Sharipov & Kalempa 2008; Doi 2010; Yap & Sader 2012, 2016).…”

Section: Introductionmentioning

confidence: 64%