Challenges in Modeling Gas-Phase Flow in Microchannels: From Slip to Transition

Barber, Robert W.; Emerson, David R.

doi:10.1080/01457630500522271

Cited by 153 publications

(69 citation statements)

References 37 publications

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“…Numerous studies include second-order velocity slip and temperature jump boundary conditions to analyze the fluid flow and heat transfer in microdevices [36][37][38][39][40][41][42][43][44][45]. The exact form of second-order slip condition and precise values of secondorder slip coefficients are not described in literature.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, researchers adopted different values of slip coefficients and varying second-order slip conditions to model the flow in the slip and transition regime. Numerous second-order slip models [37][38][39][40][41][42][43] were proposed to analyze the fluid flow and heat transfer characteristics with the choice of different slip coefficients. Recently, closed form expressions were stated for the Nusselt number using second-order velocity slip and temperature jump condition [44,45].…”

Section: Introductionmentioning

confidence: 99%

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Effects of Viscous Dissipation and Rarefaction on Parallel Plates with Constant Heat Flux Boundary Conditions

Kushwaha

Sahu

2014

Chem Eng & Technol

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The effect of viscous dissipation and rarefaction on heat transfer characteristics of hydrodynamically and thermally fully developed flow between parallel plates with constant heat flux conditions is analyzed. Three different types of heat flux boundary conditions, i.e., both plates kept at different constant heat fluxes, both plates kept at equal constant heat fluxes, and one plate insulated, are applied. In all cases, closed form expressions are obtained for the temperature distribution and Nusselt number. Viscous dissipation, rarefaction, and heat flux ratio are found to influence the heat transfer substantially. The present predictions are verified for the cases which neglect the microscale and viscous heating effect. The obtained results are in good agreement with other analytical results.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Viscous Dissipation and Rarefaction on Parallel Plates with Constant Heat Flux Boundary Conditions

Kushwaha

Sahu

2014

Chem Eng & Technol

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“…Maxwell estimated the coefficient α s by considering that the incident gas molecules have the same distributions as those of the bulk gas, and obtained α s = √ π/2, which is typically approximated by unity. However, more rigorous kinetic analyses of the Boltzmann equation for planar flows (Cercignani & Daneri (1963)) have shown that α s = 1.1466, (for more details see Barber & Emerson (2006)). Following Maxwell's original work, many other slip models have been proposed in the literature including results for atomically rough walls, for more details see the review article by Zhang et al (2012).…”

Section: Air Flow Modelmentioning

confidence: 99%

Dynamics of a small gap gas lubricated bearing with Navier slip boundary conditions

2017

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A gas lubricated bearing model is derived which is appropriate for a very small bearing face separation by including velocity slip boundary conditions and centrifugal inertia effects. The bearing dynamics are examined when an external harmonic force is imposed on the bearing due to bearing begin situated within a larger complex dynamical system. A compressible Reynolds equation is formulated for the gas film which is coupled to the bearing structure through an axial force balance where the rotor and stator correspond to spring-mass-damper systems. Surface slip boundary conditions are derived on the bearing faces, characterised by the slip length parameter. The coupled bearing system is analysed using a stroboscopic map solver with the modified Reynolds equation and structural equations solved simultaneously. For a sufficiently large forcing amplitude a flapping motion of the bearing faces is induced when the rotor and stator are in close proximity. The minimum bearing gap over the time period of the external forcing is examined for a range of bearing parameters.

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“…However, there are large variations in the second-order slip coefficient. The lack of a universally accepted second-order slip coefficient is a major problem in extending Navier-Stokes equations into the transition regime (Barber and Emerson 2006). Muzychka and Yovanovich (2002) developed a simple model for predicting the friction factor Reynolds number product in non-circular ducts for fully developed laminar continuum flow.…”

Section: Literature Reviewmentioning

confidence: 99%

Slip flow in non-circular microchannels

Duan

Muzychka

2007

Microfluid Nanofluid

115

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Microscale fluid dynamics has received intensive interest due to the emergence of MicroElectro-Mechanical Systems (MEMS) technology. When the mean free path of the gas is comparable to the channel's characteristic dimension, the continuum assumption is no longer valid and a velocity slip may occur at the duct walls. Non-circular cross sections are common channel shapes that can be produced by microfabrication. The non-circular microchannels have extensive practical applications in MEMS. Slip flow in non-circular microchannels has been examined and a simple model is proposed to predict the friction factor and Reynolds product fRe for slip flow in most non-circular microchannels. Through the selection of a characteristic length scale, the square root of crosssectional area, the effect of duct shape has been minimized. The developed model has an accuracy of 10% for most common duct shapes. The developed model may be used to predict mass flow rate and pressure distribution of slip flow in non-circular microchannels. hydraulic diameter = 4A/P E(e) complete elliptical integral of the second kind e eccentricity ¼ ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Keywords

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Challenges in Modeling Gas-Phase Flow in Microchannels: From Slip to Transition

Abstract: It has long been recognized that the fluid mechanics of gas-phase microflows

Cited by 153 publications

References 37 publications

Effects of Viscous Dissipation and Rarefaction on Parallel Plates with Constant Heat Flux Boundary Conditions

Effects of Viscous Dissipation and Rarefaction on Parallel Plates with Constant Heat Flux Boundary Conditions

Dynamics of a small gap gas lubricated bearing with Navier slip boundary conditions

Slip flow in non-circular microchannels

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