Flow of red blood cell suspensions through narrow tubes

Abstract

An experimental set up, wherein the flow of blood and red blood cell (RBC) suspensions through narrow glass capillaries can be studied, has been designed and fabricated. The set up has the facility for simultaneous measurements of various flow parameters like rate of flow, pressure drop, feed reservoir, cup-mixing and tube hematocrits. Measurements with plasma, whole blood and RBC suspensions in saline have been made in tubes of different sizes, at different flow rates and hematocrits. The anomalous effects (viz. Fahraeus–Lindquist effect and Fahraeus effect) that occur in blood flow through narrow tubes have been quantitatively studied. The experimental measurements have been analysed with the help of analytical models, to calculate the wall layer thickness and velocity profiles. Two analytical models have been used in the analysis and their range of application is discussed. The wall layer thickness at any given hematocrit is found to increase with decreasing tube size. Further, the extent of plug flow is seen to increase with increase in hematocrit.