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The Flow of Human Blood Through Capillary Tubes with Inside Diameters Between 8.7 and 221 Microns


Barbee, James Henry (1971) The Flow of Human Blood Through Capillary Tubes with Inside Diameters Between 8.7 and 221 Microns. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/3RKR-TH95.


The purpose of this study was to investigate the pressure drop­ flow rate behavior of normal human blood flowing through small capil­lary tubes. A sensitive pressure transducer was used to measure the pressure gradient along an experimental tube when various red cell suspensions passed through glass and plastic capillary tubes. In particular, the effect of capillary tube diameter on the rheological properties of blood was observed for capillary tube diameters from 8 to 221 microns.

For tubes of 221 microns and smaller, it was found that the hematocrit (volume fraction of red cells in a blood sample) of the blood flowing through a capillary tube is less than the hematocrit of the blood in the feed reservoir. The tube hematocrit decreases linearly with the logarithm of the tube diameter at constant feed reservoir hematocrit and for a given diameter tube, increases lin­early with the feed reservoir hematocrit.

An equation was developed from data taken in an 811-micron ID tube that allows the shear stress-shear rate relation to be predicted from the tube diameter, tube hematocrit, and the temperature.

It was found that the rheological properties of blood can be accurately predicted from the equation developed if the average hematocrit inside the capillary tube is used as the correct hematocrit parameter. A surprising result found is that fluid properties can be predicted for blood flow through a 29-micron ID tube; in such a tube, the equation of motion may not be valid because the "continu­ous fluid" assumption is not valid. Blood flow data were taken at 98.6°F as well as 73.5°F. Blood heated to 111°F and then cooled to 96.6°F was also investigated.

Blood flow through 15- and 9-micron ID capillaries was in­vestigated. Blood exhibits no yield stress in a 15-micron ID tube because rouleaux formation cannot restrict the flow as it does in larger tubes.

An increased yield stress was found in a 9-micron ID tube. The measured shear stress was only slightly larger (for a given U) than predicted by the continuum model in both the 15- and 9-micron ID capillary tubes.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Chemical Engineering
Degree Grantor:California Institute of Technology
Division:Chemistry and Chemical Engineering
Major Option:Chemical Engineering
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Cokelet, Giles R.
Thesis Committee:
  • Pings, Cornelius J. (chair)
Defense Date:11 December 1970
Funding AgencyGrant Number
National Heart InstituteHE 12723
National Defense Education ActUNSPECIFIED
Record Number:CaltechTHESIS:10182017-151706373
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10529
Deposited By: Benjamin Perez
Deposited On:19 Oct 2017 15:00
Last Modified:21 Dec 2019 04:41

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