Cell exclusion in couette flow: evaluation through flow visualisation and mechanical forces

Research output: Contribution to journalArticle

View graph of relations Save citation

Open

Authors

Research units

Abstract

Cell exclusion is the phenomenon whereby the hematocrit and viscosity of blood decrease in areas of high stress. While this is well known in naturally occurring Poiseuille flow in the human body, it has never previously been shown in Couette flow, which occurs in implantable devices including blood pumps. The high-shear stresses that occur in the gap between the boundaries in Couette flow are known to cause hemolysis in erythrocytes. We propose to mitigate this damage by initiating cell exclusion through the use of a spiral-groove bearing (SGB) that will provide escape routes by which the cells may separate themselves from the plasma and the high stresses in the gap. The force between two bearings (one being the SGB) in Couette flow was measured. Stained erythrocytes, along with silver spheres of similar diameter to erythrocytes, were visualized across a transparent SGB at various gap heights. A reduction in the force across the bearing for human blood, compared with fluids of comparable viscosity, was found. This indicates a reduction in the viscosity of the fluid across the bearing due to a lowered hematocrit because of cell exclusion. The corresponding images clearly show both cells and spheres being excluded from the gap by entering the grooves. This is the first time the phenomenon of cell exclusion has been shown in Couette flow. It not only furthers our understanding of how blood responds to different flows but could also lead to improvements in the future design of medical devices.

Documents

  • Cell exclusion in couette flow

    Rights statement: Leslie, L. J., Marshall, L. J., Devitt, A., Hilton, A., & Tansley, G. D. (2013). Cell exclusion in couette flow: evaluation through flow visualisation and mechanical forces. Artificial organs, 37(3), 267-275., which has been published in final form at http://dx.doi.org/10.1111/j.1525-1594.2012.01561.x © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

    Accepted author manuscript, 277 KB, PDF-document

Details

Original languageEnglish
Pages (from-to)267-275
Number of pages9
JournalArtificial Organs
Volume37
Issue number3
Early online date29 Jan 2013
DOIs
Publication statusPublished - Mar 2013

Bibliographic note

Leslie, L. J., Marshall, L. J., Devitt, A., Hilton, A., & Tansley, G. D. (2013). Cell exclusion in couette flow: evaluation through flow visualisation and mechanical forces. Artificial organs, 37(3), 267-275., which has been published in final form at http://dx.doi.org/10.1111/j.1525-1594.2012.01561.x © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

    Keywords

  • erythrocytes, hemolysis, hemorrheology, packed red-cell volume, ventricular assist device

Download statistics

No data available

Employable Graduates; Exploitable Research

Copy the text from this field...