The dynamic viscosity of some human blood 1

Abstract

Measurements were made of the stress-strain behavior of human blood during two transition sequences (from rest to eventually a 25 sec⁻¹ strain rate, and from 64 sec⁻¹ to an eventual 127 sec⁻¹ strain rate) in a modified Brookfield cone-and-plate viscometer. The data were obtained laboriously from movies of the viscometer and a stop watch at 24 and 64 frames/sec, respectively, and are shown in Figs. 1 and 2. These show major changes of stress (in both experiments) prior to any appreciable changes of the strain rates of the blood. The first experiment shows a yield stress of about 0.5 dyne/cm², jerky starting of the blood, and an eventual fluidity of 10.5 cm sec/g. The second experiment shows first a prompt fluidity fall from 14 to 9 cm sec/g with rising stress and almost constant strain rate, then most of 2 sec at about fluidity 9, a sudden jump to about fluidity 15 (accompanied by a sharp drop in actual stress to near its eventual value), and subsequent marked oscillations of strain rate and fluidity. In this interval the fluidity passed through a maximum above 20 and then settled down to an eventual value of 16 cm sec/g.