چكيده به لاتين
In the present study, the interaction of pulsatile blood flow in the carotid artery with different severities of stenosis and for different pulse rates is examined numerically. For modeling non-Newtonian blood fluid and hyperelastic arterial wall, Carreau-Yasuda non-Newtonian model and modified Mooney-Rivin hyperplastic model are used, respectively. Using the fluid-structure interaction method and the arbitrary Lagrangian-Eulerian (ALE) method in COMSOL Multiphysics software and using the finite element method, the effect of different severities of stenosis, the effect of different pulse rate, the effect of arterial wall properties and the effect of increased blood viscosity are examined.
The results showed, with stenosis severity increasing from 25% to 75% in the pulse rate of 60 bpm and at the time of maximum flow rate, the maximum value of axial velocity and maximum wall shear stress increased 8.21 and 37.12 times, respectively. In addition, with pulse rate increasing from 60 bpm to 108 bpm and in the severe stenosis of 75%, its maximum wall shear stress increases 2.08 times. By Comparing the maximum wall shear stresses with the threshold shear stress expressed by Leverett et al, it was found that in stenosis severity of 25% and 50% and for all three pulse rates, relatively little damage is done to red blood cells, but in the severe stenosis of 75% and for all three pulse rates, due to the fact that the maximum shear stresses of the threshold shear stress are higher, a large amount of hemolysis occurs.
In addition, with the progression of atherosclerosis (elastic modulus increasing from 500 kPa to 2 MPa), it was found that the maximum value of wall shear stress at pulse rate of 60 bpm and in the severe stenosis of 75% increased by about 65.02%. It has also been shown that the use of hyperelastic models for the arterial wall leads to lower axial velocity, lower blood pressure, higher radial displacement, and lower shear stresses. The results also showed that with increasing blood viscosity, blood pressure and, consequently, wall radial displacement increased, and the maximum value of wall shear stress increased by about 14.17%.
