A concentrated suspension model for the couette rheology of blood

A simple “cell” method for concentrated suspensions has been used to construct a model for the rheological behavioi of blood. The model includes the physical pioperties of the suspending medium, red cell membrane and red cell fluid content. Predictions of the gross viscosity of red cell suspensions are found to agree very well with experiment in the cases of hardened red cells (or normal red cells at very low shear rate) and of normal red cells in the asyniptotic limit of high shear rates. The behavior at intermediate shear rates requires a knowledge of the visco‐plastic properties of the membrane and a number of membrane models are investigated. Of particular interest is a plastic membrane which employs a membrane yield stress obtained from other experiments and whose results are qualitatively in agreement with the viscometric data at these intermediate shear rates.