First passage measurements of dispersion coefficients for suspension flows

Eugene C. Eckstein, Mark Leggas

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

We report results of an experimental protocol for determining effective diffusion coefficients in suspension flows in thin channels. The method is based on the first-passage method (FPM), a well-known aspect of probability theory. Images of identifiable individual particles are collected at a regular rate by a video camera. The times needed for individual particles to move selected distances on either side of the original position are measured. Such events are individually the 'first passage' for the selected net distances. Repeated evaluation of this statistic for the same initial conditions is done so that the history of axial motion can be summarized in a statistical manner. All images are collected in a moving frame of reference in order to limit more precisely the initial time and to make observations in a specified region of the flow. The protocol has been used in rectangular channels approximately 50 micrometers high and 500 micrometers wide to collect observations that were located approximately 12 microns in the narrow direction down from the upper surface. The local shear rate is estimated to be 100 inverse seconds. A dilute suspension of beads and a 25% suspension (volume/volume) of erythrocytes was used. Values that were measured compared well with those predicted by the Stokes-Einstein equation and with published data for blood flows.

Original languageEnglish
Title of host publicationAmerican Society of Mechanical Engineers, Bioengineering Division (Publication) BED
Pages57-58
Number of pages2
Volume43
StatePublished - 1999
EventAdvances in Bioengineering - 1999 (The ASME International Mechanical Engineering Congress and Exposition) - Nashville, TN, USA
Duration: Nov 14 1999Nov 19 1999

Conference

ConferenceAdvances in Bioengineering - 1999 (The ASME International Mechanical Engineering Congress and Exposition)
CityNashville, TN, USA
Period11/14/9911/19/99

ASJC Scopus subject areas

  • General Engineering

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