A SHEAR-THINNING VISCOELASTIC FLUID MODEL FOR DESCRIBING THE FLOW OF BLOOD

Abstract

progress by the flow characteristics of blood (10, 13). The relevance of computational simulations in the development of cardiovascular A model is developed for the flow of blood, within a thermodynamic devices, in particular blood pumps, has been highlighted in a recent framework that takes cognizance of the fact that viscoelastic fluids article (3), and there is a need for powerful, yet simple, models that can remain stress free in several configurations, ie, such bodies have can capture the complex rheological response of blood over a range of multiple natural configurations (see Rajagopal (19), Rajagopal and flow conditions. In this article, we advance a model for blood and Srinivasa (20)). This thermodynamic framework leads to blood being investigate its efficacy under conditions of steady and oscillatory characterized by four independent parameters that reflect the flow. elasticity, the viscosity of the plasma, the formation of rouleaus and Blood consists in multiple constituents namely red blood cel1s their effect on the viscosity of blood, and the shear thinning that takes (RBCs), white blood cells, platelets, etc, suspended in a medium place during the flow. The model emerges in a hierarchy of (plasma) of proteins and water, The plasma is a Newtonian fluid. The increasingly complex nonsimple viscoelastic fluid models, and in this haematocrit (cel1 matter that consists primarily of RBCs) forms study two other models in the same class (proposed by Rajagopal and approximately 45% of the volume of normal human blood. Chien, et Srinivasa (20)) are also considered, The efficacy of these models in al (4, 5) were among the earliest to relate the shear-thinning nature of describing the response of blood is investigated. Among the models blood to the tendency of RBC-rouleau aggregates (which form at low studied, the proposed model is not only best able to describe the shear) to disaggregate upon the application of shear. Upon increasing response of blood but is the first to have rigorous thermodynamic the shear rate, the RBCs become :fluid-like' and lose their ability to moorings, The predictions of the model agree exceptional1y wel1 with store elastic energy (24); they also align themselves with the flow the data that is available for steady flow and osci11atory flow field and tend to slide upon plasma layers formed in between (32). experiments, while the two other models are inadequate to describe Thurston (27) was among the earliest to recognize the viscoelastic oscillatory flows (a serious shortcoming as osci11atory flows are the nature of blood, and that the viscoelastic behavior is less prominent most natural flows that blood undergoes).