Licentiate seminar

Unsteadiness of blood flow in 90-degree bifurcations

Defendant Main Advisor Extra Advisor Date
Stevin van Wyk Laszlo Fuchs Lisa Prahl Wittberg 2011-12-08

Staffan Lundström,

Evaluation committee


The blood is a complex fluid that contains, in addition to water, cells, macromolecules and a large number of smaller molecules. The physical properties of the blood are therefore the result of non-linear combination of its constituents. Hence, the blood viscosity depends on the local flow field itself. The local blood viscosity conditions determine the local concentration of the blood constituents. This study considers blood like flows in generalised 90-degree arterial bifurcations relevant to the large aortic branches in humans. It is shown that the Red Blood Cell (RBC) distribution in the region of bifurcations may lead to changes in concentration. This implies changes to the viscosity that changes the fluid mechanical properties in the near wall regions, for example, playing a role in arterial disease development. Furthermore, it is shown that oscillatory wall shear stresses, are affected by changes in RBC concentration in the regions of the bifurcation associated with atherogenesis. More importantly, an intrinsic rheological property of blood, in conjunction with stagnation in separated flows, may be responsible for elevated temporal wall shear stress gradients influencing endothelial cell function.
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