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The purpose of this work is to predict the effect of impaired red blood cells (RBCs) deformability on blood flow conditions in human carotid artery bifurcation. First, a blood viscosity model is developed that predicts the steady-state blood viscosity as a function of shear rate, plasma viscosity, and mechanical (and geometrical) properties of RBC's. Viscosity model is developed by modifying the well-known Krieger and Dougherty equation for monodisperse suspensions by using the dimensional analysis approach. With the approach, we manage to account for the microscopic properties of RBC's, such as their deformability, in the macroscopic behavior of blood via blood viscosity. In the second part of the paper, the deduced viscosity model is used to numerically predict blood flow conditions in human carotid artery bifurcation. Simulations are performed for different values of RBC's deformability and analyzed by investigating parameters, such as the temporal mean wall shear stress (WSS), oscillatory shear index (OSI), and mean temporal gradient of WSS. The analyses show that the decrease of RBC's deformability decrease the regions of low WSS (i.e., sites known to be prevalent at atherosclerosis-prone regions); increase, in average, the value of WSS along the artery; and decrease the areas of high OSI. These observations provide an insight into the influence of blood's microscopic properties, such as the deformability of RBC's, on hemodynamics in larger arteries and their influence on parameters that are known to play a role in the initiation and progression of atherosclerosis. [ABSTRACT FROM AUTHOR]

Mathematical modelling of thermo-mechanical processes, such as welding and heat treatment processes, requires the choice of an appropriate material constitutive model on one hand and the use of a consistent set of material parameters on the other. However, possible untrustworthiness of the material parameters contained in the adopted constitutive model, in particular regarding their dependence on temperature, could significantly impact the physical objectivity of the obtained numerical results. Despite the fact that the accuracy of a constitutive model increases with the number of considered material parameters in general, the analyses performed in this paper are based on a relatively simple, but still adequate elastic-viscous-plastic constitutive model. First, by an inverse numerical procedure the temperature-dependent thermal and mechanical material parameters are identified from given experimental data for an austenite stainless steel 316L (AISI). Second, the adequacy of the adopted model and identified material parameters is shown by simulating numerically a threepass butt welding experiment where good agreement between the calculated results and data from the literature is found. Lastly, annealing of the welded plate for residual stress relief was simulated numerically. The obtained reduction in residual stresses is found to be in agreement with the amount of the residual stress reduction provided from literature. The appropriateness of using a viscous power constitutive law and the adequacy of the presented material characterisation procedure in the modelling of thermo-mechanical processes is demonstrated. [ABSTRACT FROM AUTHOR]