Backward-Facing Step Flow in Microchannels Using Microparticle Image Velocimetry

    Authors

    E. Yakhshi-Tafti; H. J. Cho;R. Kumar

    Comments

    Authors: contact us about adding a copy of your work at [email protected]

    Abbreviated Journal Title

    J. Thermophys. Heat Transf.

    Keywords

    Thermodynamics; Engineering, Mechanical

    Abstract

    Flow at a backward-facing step feature (1:5 expansion ratio) in a microchannel has been studied using microparticle image velocimetry. The onset and development of a recirculation flow was studied as a function of flow rate. The onset of recirculation was initiated at flow rates that correspond to Reynolds numbers, Re > 95. The dimensions are such that recirculation flow has a three-dimensional structure and is expected to vary with the depth coordinate. Because of volume illumination, most microparticle-image-velocimetry measurements provide two-dimensional averaged flow profiles. Flow at the backward-facing step offers the opportunity to investigate the ability of resolving the depth dependency by conventional microparticle image velocimetry in relevance to two parameters: variation of the focus plane depth z* and using variable time intervals for particle-image-velocimetry image pairs Delta t. The ensemble cross-correlation algorithm was found to be insensitive to the variation of z* for low magnification (4x) but was able to resolve the parabolic nature of flow across the depth of the channel, when high magnification objective lenses were used (20x). For a given flow rate and constant z*, the variation of At resulted in quantitatively and qualitatively different flow patterns, suggesting that Delta t is an indirect means Delta t of resolving the depth as the correlation algorithm locks onto a flow plane with particles moving at a speed that can be resolved with the given process parameters and time interval.

    Journal Title

    Journal of Thermophysics and Heat Transfer

    Volume

    25

    Issue/Number

    1

    Publication Date

    1-1-2011

    Document Type

    Article; Proceedings Paper

    Language

    English

    First Page

    96

    Last Page

    103

    WOS Identifier

    WOS:000287639300010

    ISSN

    0887-8722

    Share

    COinS
     

    Accessibility Statement

    This item was created or digitized prior to April 24, 2027, or is a reproduction of legacy media created before that date. It is preserved in its original, unmodified state specifically for research, reference, or historical recordkeeping. In accordance with the ADA Title II Final Rule, the University Libraries provides accessible versions of archival materials upon request. To request an accommodation for this item, please submit an accessibility request form.