Momentum and mass fluxes in a gas confined between periodically structured surfaces at different temperatures

Donkov, A. A.; Tiwari, Sudarshan; Liang, Tengfei; Hardt, Steffen; Klar, Axel; Ye, Wenjing

doi:10.1103/physreve.84.016304

Cited by 33 publications

(57 citation statements)

References 17 publications

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“…To start with, we consider the collisionless regime, since here an analytical expression can be obtained for the force on the upper or lower wall and vanes, respectively. The force calculation proceeds along the lines of Donkov et al [15]. The force density at position r s on a wall is…”

Section: Collisionless Regimementioning

confidence: 99%

“…Practically implementable designs can be accomplished based on a periodic temperature profile along the walls of a channel [11][12][13], or by inducing thermal edge flow at an array of heated plates stacked within a channel [14]. An alternative implementation was recently proposed by Donkov et al [15], where the gas flow is induced between surfaces held at different temperatures. Here, one of the surfaces is considered to be structured in a ratchet pattern, with the inclined face of the ratchet reflecting gas molecules specularly, while the rest of the boundary reflects diffusely.…”

Section: Introductionmentioning

confidence: 99%

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Knudsen pump inspired by Crookes radiometer with a specular wall

et al. 2017

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A rarefied gas is considered in a channel consisting of two infinite parallel plates between which an evenly spaced array of smaller plates is arranged normal to the channel direction. Each of these smaller plates is assumed to possess one ideally specularly reflective and one ideally diffusively reflective side. When the temperature of the small plates differs from the temperature of the sidewalls of the channel, these boundary conditions result in a temperature profile around the edges of each small plate which breaks the reflection symmetry along the channel direction. This in turn results in a force on each plate and a net gas flow along the channel. The situation is analysed numerically using the direct simulation Monte Carlo (DSMC) method and compared with analytical results where available. The influence of the ideally specularly reflective wall is assessed by comparing with simulations using a finite accommodation coefficient at the corresponding wall. The configuration bears some similarity with a Crookes radiometer, where a non-symmetric temperature profile at the radiometer vanes is generated by different temperatures on each side of the vane, resulting in a motion of the rotor. The described principle may find applications in pumping gas on small scales driven by temperature gradients

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Section: Collisionless Regimementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Knudsen pump inspired by Crookes radiometer with a specular wall

et al. 2017

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“…In addition to the earlier proposed Knudsen pump [5,6], capillaries with ratchet surfaces have the potential for other possible configurations [12]. The driving mechanism of these systems has been analyzed by Wüger [12] as well as Hardt et al [13], and the mass and momentum transfer has been studied by Donkov et al [14].…”

Section: Introductionmentioning

confidence: 99%

Onsager's cross coupling effects in gas flows confined to micro-channels

Wang

et al. 2016

Phys. Rev. Fluids

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In rarefied gases, mass and heat transport processes interfere with each other, leading to the mechano-caloric effect and thermo-osmotic effect, which are of interest to both theoretical study and practical applications. We employ the unified gas-kinetic scheme to investigate these cross coupling effects in gas flows in micro-channels. Our numerical simulations cover channels of planar surfaces and also channels of ratchet surfaces, with Onsager's reciprocal relation verified for both cases. For channels of planar surfaces, simulations are performed in a wide range of Knudsen number and our numerical results show good agreement with the literature results. For channels of ratchet surfaces, simulations are performed for both the slip and transition regimes and our numerical results not only confirm the theoretical prediction [Phys. Rev. Lett. 107, 164502 (2011)] for Knudsen number in the slip regime but also show that the off-diagonal kinetic coefficients for cross coupling effects are maximized at a Knudsen number in the transition regime. Finally, a preliminary optimization study is carried out for the geometry of Knudsen pump based on channels of ratchet surfaces.

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“…Micro-and nanoscale thermally driven gas transport has become an active research topic in recent years due to the interesting phenomena arising from small spatial scales such as thermophoresis, thermal transpiration, and the Knudsen force [1][2][3][4]. These noncontinuum phenomena not only are of scientific interest but also have important applications in the aerosol industry and microelectromechanical and nanoelectromechanical systems (MEMS/NEMS), for example, thermal-transpiration-based micro gas pumps [5,6].…”

Section: Introductionmentioning

confidence: 99%

Performance evaluation of Maxwell and Cercignani-Lampis gas-wall interaction models in the modeling of thermally driven rarefied gas transport

Liang

2013

Phys. Rev. E

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CitationPerformance evaluation of Maxwell and CercignaniLampis gas-wall interaction models in the modeling of thermally driven rarefied gas transport 2013, 88 (1) Physical Review E A systematic study on the performance of two empirical gas-wall interaction models, the Maxwell model and the Cercignani-Lampis (CL) model, in the entire Knudsen range is conducted. The models are evaluated by examining the accuracy of key macroscopic quantities such as temperature, density, and pressure, in three benchmark thermal problems, namely the Fourier thermal problem, the Knudsen force problem, and the thermal transpiration problem. The reference solutions are obtained from a validated hybrid DSMC-MD algorithm developed in-house. It has been found that while both models predict temperature and density reasonably well in the Fourier thermal problem, the pressure profile obtained from Maxwell model exhibits a trend that opposes that from the reference solution. As a consequence, the Maxwell model is unable to predict the orientation change of the Knudsen force acting on a cold cylinder embedded in a hot cylindrical enclosure at a certain Knudsen number. In the simulation of the thermal transpiration coefficient, although all three models overestimate the coefficient, the coefficient obtained from CL model is the closest to the reference solution. The Maxwell model performs the worst. The cause of the overestimated coefficient is investigated and its link to the overly constrained correlation between the tangential momentum accommodation coefficient and the tangential energy accommodation coefficient inherent in the models is pointed out. Directions for further improvement of models are suggested.

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Momentum and mass fluxes in a gas confined between periodically structured surfaces at different temperatures

Cited by 33 publications

References 17 publications

Knudsen pump inspired by Crookes radiometer with a specular wall

Knudsen pump inspired by Crookes radiometer with a specular wall

Onsager's cross coupling effects in gas flows confined to micro-channels

Performance evaluation of Maxwell and Cercignani-Lampis gas-wall interaction models in the modeling of thermally driven rarefied gas transport

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