Heat flux between parallel plates through a binary gaseous mixture over the whole range of the Knudsen number

Sharipov, Felix; Cumin, Liliana M. Gramani; Kalempa, Denize

doi:10.1016/j.physa.2006.11.077

Cited by 39 publications

(45 citation statements)

References 27 publications

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“…This important transition has been investigated in semiconductor and dielectric thin films, 1 carbon nanotubes, 2,3 the Brownian motion of particles in a liquid, 4 the heat wave transport in strongly scattering thin samples, 5 the optical imaging of biological tissues, 5 and the heat transport in rarefied gases, [6][7][8][9][10][11] to cite some examples. Although heat propagation in rarefied air have been widely studied under steady-state conditions, [6][7][8][9][10][11] it has not yet been fully explored under a modulated thermal excitation, 22,23 which is addressed in the present work.…”

Section: Introductionmentioning

confidence: 99%

Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber

et al. 2017

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Modulated heat transfer in air subject to pressures from 760 Torr to 10-4 Torr is experimentally studied by means of a thermal-wave resonant cavity placed in a vacuum chamber. This is done through the analysis of the amplitude and phase delay of the photothermal signal as a function of the cavity length and pressure through of the Knudsen’s number. The viscous, transitional, and free molecular regimes of heat transport are observed for pressures P>1.5 Torr, 25 mTorr<P<1.5 Torr, and P<25 mTorr; respectively. It is shown that the fingerprint of each regime is determined by the concavity of the amplitude decay in a length scan, which is concave upward for the viscous regime and concave downward in the free molecular one. Furthermore, the increase of the radiative contribution on both the amplitude and phase is also observed as the pressure reduces. The obtained results show that the proposed methodology can be used to study the molecular dynamics in gases supporting diffusive and ballistic heat transport.

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Section: Introductionmentioning

confidence: 99%

Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber

et al. 2017

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“…Here, however, for T A /T B ≥ 10, as δ 0 is increased, the heat flux is initially increased and then at some δ 0 is reduced. It is noted that for δ 0 = 0 and δ 0 = 150, which correspond to the free molecular and hydrodynamic limits, the agreement with the corresponding analytical results presented in [179,176] is at least two significant figures.…”

Section: Heat Transfer Between Parallel Platessupporting

confidence: 74%

“…The problem of heat transfer between parallel plates has been studied extensively, both for single gases [171,172,173,174,175] and mixtures [176] in the whole range of the Knudsen number. Even more, it has been used to benchmark the efficiency of several semi-analytical and numerical methods solving kinetic equations [177,99,178].…”

Section: Non-linear Heat Transfermentioning

confidence: 99%

Simulation of transport phenomena in conditions far from thermodynamic equilibrium via kinetic theory with applications in vacuum technology and MEMS

Πανταζής¹

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The approval of the current dissertation by the Department of Mechanical Engineering of the University of Thessaly does not imply acceptance of the author's opinions (Law 5343/32 number 202 paragraph 2). Also, the views and opinions expressed herein do not necessarily reflect those of the European Commission. There are several other people who I feel that have contributed in the writing of this dissertation.The most important contributions, along with several helpful conversations, were made by Prof. F.Sharipov, who provided the basic concept of the channel end effect study, and Dr. Chr. Day along with the KIT personnel, who briefly introduced me in the world of experimental rarefied gas dynamics. It was also a priviledge to discuss and work for a brief period of time with Prof. A. Grecos, who tirelessly discussed with me on various subjects of statistical mechanics. Financial support for this Ph.D. has been provided by the Euratom Association -Hellenic Republic, to which I am deeply indepted. Also, partial support for conference mobility expenses has been received from the GASMEMS Marie Curie programme. In this work, non-equilibrium transport phenomena have been examined via the kinetic theory of gases. The behaviour of the gas in low pressure conditions or in low-dimensionality systems can not be captured by the usual Navier-Stokes formulation, in conjunction with the constitutive laws of Newton-Fourier-Fick. The limited number of intermolecular collisions results in departure from equilibrium and the particulate nature of the gas must be taken into account, greatly increasing the computational effort.The problem is described by the integro-differential Boltzmann equation, which is used to determine the distribution of particles in physical and molecular velocity space, as well as in time.There are difficulties associated with the seven-dimensional nature of the distribution function, as well as with the complexity of the collision term, which is usually substituted by an appropriate model.The most widely used and successful numerical methodologies, the Discrete Velocity Method (DVM) and the Direct Simulation Monte Carlo (DSMC), are applied here in the whole range of the Knudsen number. It is important to employ approaches based on kinetic theory, since these are the only ones which are valid for any rarefaction level.In this work, several problems including non-equilibrium phenomena are considered. The interaction of gases with solid surfaces is considered for several problems according to the CercignaniLampis boundary conditions. The non-linear form of this scattering kernel, which had not been pre- viously used in the literature, is applied on the problem of heat transfer between parallel plates and coaxial cylinders. Its linearized form has also been employed for both flow and heat transfer problems and a comparison with relevant experiments has lead to surface characterization with respect to argon and helium flows.Non-linear heat conduction phenomena are also studied for the parallel plates and coaxial c...

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“…This deviation stems from the fact that in this case the Knudsen number based on the plate distance, /h = 0.25, is relatively small, and it is necessary to take into account the temperature jumps at the upper and lower boundaries of the simulation domain in order to obtain the correct heat flux between the plates. For /h 0.5 the heat flux between parallel plates at a distance h is approximated well as [43,44]…”

Section: A Dsmc Simulation Of Rotating Janus Spherementioning

confidence: 99%

Thermophoresis of Janus particles at large Knudsen numbers

Baier¹,

Tiwari²,

Shrestha³

et al. 2018

Phys. Rev. Fluids

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The force and torque on a Janus sphere moving in a rarefied gas with a thermal gradient are calculated. The regime of large Knudsen number is considered, with the momenta of impinging gas molecules either obtained from a Chapman-Enskog distribution or from a binary Maxwellian distribution between two opposing parallel plates at different temperature. The reflection properties at the surface of the Janus particle are characterized by accommodation coefficients having constant but dissimilar values on each hemisphere. It is shown that the Janus particle preferentially orients such that the hemisphere with a larger accommodation coefficient points towards the lower temperature. The thermophoretic velocity of the particle is computed, and the influence of the thermophoretic motion on the magnitude of the torque responsible for the particle orientation is studied. The analytical calculations are supported by Direct Simulation Monte Carlo results, extending the scope of the study towards smaller Knudsen numbers. The results shed light on the efficiency of oriented deposition of nanoparticles from the gas phase onto a cold surface. arXiv:1807.04987v1 [physics.flu-dyn]

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Heat flux between parallel plates through a binary gaseous mixture over the whole range of the Knudsen number

Cited by 39 publications

References 27 publications

Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber

Diffusive-to-ballistic transition of the modulated heat transport in a rarefied air chamber

Simulation of transport phenomena in conditions far from thermodynamic equilibrium via kinetic theory with applications in vacuum technology and MEMS

Thermophoresis of Janus particles at large Knudsen numbers

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