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In Situ Control of Gas Flow by Modification of Gas-Solid Interactions

Dongjin Seo and William A. Ducker
Phys. Rev. Lett. 111, 174502 – Published 25 October 2013; Erratum Phys. Rev. Lett. 112, 159904 (2014)
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Abstract

The boundary condition for gas flow at the solid-gas interface can be altered by in situ control of the state of a thin film adsorbed to the solid. A monolayer of ocatadecyltrichlorosilane (OTS) reversibly undergoes a meltinglike transition. When the temperature of an OTS-coated particle and plate is moved through the range of OTS “melting” temperatures, there is a change in the lubrication force between the particle and plate in 1 atm of nitrogen gas. This change is interpreted in terms of a change in the flow of gas mediated by the slip length and tangential momentum accommodation coefficient (TMAC). There is a minimum in slip length (290 nm) at 18°C, which corresponds to a maximum in TMAC (0.44). The slip length increases to 590 nm at 40°C which corresponds to a TMAC of 0.25. We attribute the decrease in TMAC with increasing temperature to a decrease in roughness of the monolayer on melting, which allows a higher fraction of specular gas reflections, thereby conserving tangential gas momentum. The importance of this work is that it demonstrates the ability to control gas flow simply by altering the interface for fixed geometry and gas properties.

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  • Received 24 June 2013

DOI:https://doi.org/10.1103/PhysRevLett.111.174502

© 2013 American Physical Society

Erratum

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Controlling Flow with a Roughness Knob

Published 25 October 2013

A new technique for controlling gas flow through microchannels involves adjusting the surface roughness of a thin film coating the walls.

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Authors & Affiliations

Dongjin Seo and William A. Ducker*

  • Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, USA

  • *To whom all correspondence should be addressed. wducker@vt.edu

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Issue

Vol. 111, Iss. 17 — 25 October 2013

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