A study on the constitutive equation of blood

This paper proposes and studies a new three-parameter constitutive equation for whole human blood. The model aims at a proper description of the shear thinning behavior of blood at both low and high shear rates. While empirically based, it relies on continuum constitutive theories. The model has been verified by fitting the experimental data available in the literature using the weighted least squares. Results show that the proposed model fits the experimental data with nearly constant parameters in a wide shear range, and with average deviations ε̄ less than 6.24%. Formulae to calculate the velocity profile and flow rate of the proposed model in a straight tube flow were deduced. Compared to Casson's and Newtonian models, it is concluded that the proposed model is more effective in describing the shear thinning behavior of blood within a wide shear range

Non-Newtonian flow patterns associated with an arterial stenosis

A non-Newtonian constitutive equation for blood has been introduced in this paper. Using this equation, blood flow attributes such as velocity profiles, flowrate, pressure gradient, and wall shear stress in both straight and stenotic (constricted) tubes have been examined. Results showed that compared with Newtonian flow at the same flowrate, the non-Newtonian normally features larger pressure gradient, higher wall shear stress, and different velocity profile, especially in stenotic tube. In addition, the non-Newtonian stenotic flow appears to be more stable than Newtonian flow

Velocity, pressure and shear stress distributions in a pulsatile stenotic flow

No abstract available

Finite element analysis of pulsatile flow patterns associated with an arterial stenosis

No abstract available

Finite element analysis of pulsatile flow patterns associated with an arterial stenosis

No abstract available

Velocity, pressure and shear stress distributions in a pulsatile stenotic flow

No abstract available

A nonlinear anisotropic model for porcine aortic heart valves

The anisotropic property of porcine aortic valve leaflet has potentially significant effects on its mechanical behaviour and the failure mechanisms. However, due to its complex nature, testing and modelling the anisotropic porcine aortic valves remains a continuing challenge to date. This study has developed a nonlinear anisotropic finite element model for porcine heart valves. The model is based on the uniaxial experimental data of porcine aortic heart valve leaflet and the properties of nonlinear composite material. A finite element code is developed to solve this problem using the 8-node super-parameter nonlinear shells and the update Lagrangian method. The stress distribution and deformation of the porcine aortic valves with either uniform and non-uniform thicknesses in closed phase and loaded condition are calculated. The results showed significant changes in the stress distributions due to the anisotropic property of the leaflets. Compared with the isotropic valve at the same loading condition, it is found that the site of the peak stress of the anisotropic leaflet is different; the maximum longitudinal normal stress is increased, but the maximum transversal normal stress and in-plane shear stress are reduced. We conclude that it is very important to consider the anisotropic property of the porcine heart valves in order to understand the failure mechanism of such valves in vivo