Spatially uniform microflows induced by thermoviscous expansion along a traveling temperature wave: analogies with electro-osmotic transport

Pal, Debashis ; Chakraborty, Suman (2012) Spatially uniform microflows induced by thermoviscous expansion along a traveling temperature wave: analogies with electro-osmotic transport Physical Review E, 86 (1). Article ID 016321. ISSN 1539-3755

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Official URL: http://journals.aps.org/pre/abstract/10.1103/PhysR...

Related URL: http://dx.doi.org/10.1103/PhysRevE.86.016321

Abstract

We discover that thermoviscous expansion along a traveling wave in a microfluidic channel may be capable of generating a spatially uniform flow profile in a time-averaged sense. We further delineate that the resultant complex flow characteristics, realized by virtue of an intricate interplay between thermal compression-expansion waves and temperature-dependent viscosity variations and controlled by an external heating, may be remarkably characterized by a unique thermal penetration depth scale (analogous to Debye length in electro-osmosis) and a velocity scale (analogous to the Helmholtz Smulochowski velocity in electro-osmosis) that in turn depends on the considerations of “thin” and “thick” microchannel limits, as dictated by the thermal penetration depth as compared to the lateral extent of the microfluidic channel. We show that, when the thermal penetration depth is small as compared to the channel height, a uniform velocity profile is generated in the channel in a time-averaged sense. The velocity scale characterizing this uniform flow may be represented by a function of the thermal diffusivity, volumetric expansion coefficient and thermal viscosity coefficient of the fluid, characteristic amplitude and speed of the thermal wave, as well as the channel height. Results from the present study are expected to provide valuable insights towards arresting hydrodynamic dispersion in microchannels by nonelectrochemical means, following a pH-independent route.

Item Type:Article
Source:Copyright of this article belongs to American Physical Society.
ID Code:100757
Deposited On:23 Dec 2016 06:09
Last Modified:23 Dec 2016 06:09

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