Comparison Of Newtonian And Non-Newtonian Blood Flow In Ascending Aortic Aneurysm

Aleksandra Petuchova1 and Algirdas Maknickas2
1Department of Biomechanical Engineering, Faculty of Mechanics, Vilnius Gediminas Technical University, Basanavičiaus str. 28, 2Laboratory of Numerical Simulation, Institute of Mechanics, Faculty of Mechanics, Vilnius Gediminas Technical University, Basanavičiaus str. 28


Aims: The aim of this work is to perform a numerical study of aortic hemodynamics and to evaluate the parameters of the ascending aortic aneurysm when blood is modeled as a non-Newtonian fluid and a Newtonian fluid using COMSOL software. Methods: The ascending aorta model was constructed from a medical CT image. The finite element method laminar blood flow modelling of six cardiac cycles was performed at different blood parameters. Navier-Stokes equations for an incompressible fluid were used to simulate blood flow in the CFD tool. The inflow boundary conditions were a flow waveform that approximates the systolic and diastolic phases. The outflow boundary conditions were set as pressure at each outlet that varies with time as a function. The first solution was calculated by considering blood as a Newtonian fluid, in the second solution, blood was assumed to be a non-Newtonian fluid using the Carreau model. Results: The results showed that the highest blood flow velocities were 0.806 m/s in the aorta model with Newtonian fluid and 0.820 m/s in the non-Newtonian during systole. There were changes in the blood velocity streamlines during diastole. The distribution of the wall shear stress (WSS) plot on the aneurysm surface showed changes: In the non-Newtonian simulation, the systolic WSS values were 0.3 Pa, Newtonian values were 0.2 Pa. Highest time-average one cycle WSS values were 2 Pa for both non-Newtonian and Newtonian cases. Conclusions: According to investigation of two types of fluids as Newtonian and non-Newtonian, the general conclusions were made: the average systolic velocities and diastolic velocities were 2% and 9% higher in the non-Newtonian fluid. The WSS values at the aneurysm surface were higher 30% in non-Newtonian simulation during systole and the average WSS at the surface of the artery in diastole was 20% higher in Newtonian fluid.