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Surface obstacles in pulsatile flow

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Abstract

Flows past obstacles mounted on flat surfaces have been widely studied due to their ubiquity in nature and engineering. For nearly all of these studies, the freestream flow over the obstacle was steady, i.e., constant velocity, unidirectional flow. Unsteady, pulsatile flows occur frequently in biology, geophysics, biomedical engineering, etc. Our study is aimed at extending the comprehensive knowledge base that exists for steady flows to considerably more complex pulsatile flows. Characterizing the vortex and wake dynamics of flows around surface obstacles embedded in pulsatile flows can provide insights into the underlying physics in all wake and junction flows. In this study, we experimentally investigate the wake of two canonical obstacles: a cube and a circular cylinder with an aspect ratio of unity. Our previous studies of a surface-mounted hemisphere in pulsatile flow are used as a baseline for these two new, more complex geometries. Phase-averaged PIV and hot-wire anemometry are used to characterize the dynamics of coherent structures in the wake and at the windward junction of the obstacles. Complex physics occur during the deceleration phase of the pulsatile inflow. We propose a framework for understanding these physics based on self-induced vortex propagation, similar to the phenomena exhibited by vortex rings.

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Authors and Affiliations

  1. Biofluid Dynamics Laboratory, The George Washington University, Washington, DC, USA

    Ian A. Carr

  2. Department of Mechanical and Aerospace Engineering, The George Washington University, 800 22nd St. NW, Washington, DC, 20052, USA

    Michael W. Plesniak

Authors
  1. Ian A. Carr
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  2. Michael W. Plesniak
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Correspondence to Michael W. Plesniak.

Additional information

This material is based upon work supported by the National Science Foundation under Grant number CBET-1236351.

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Carr, I.A., Plesniak, M.W. Surface obstacles in pulsatile flow. Exp Fluids 58, 152 (2017). https://doi.org/10.1007/s00348-017-2436-5

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  • DOI: https://doi.org/10.1007/s00348-017-2436-5

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