Comprehensive analysis of arterial macromolecule transport utilizing a novel multi-layer porous media approach and the effects of gender-related geometrical characteristics of aorta-iliac bifurcation.

摘要

Works pertinent to arterial transport models are analyzed and a critical assessment of the models utilized in the study of fluid flow and mass transfer within the arteries is presented with an emphasis on the role of porous media. Arterial transport models are classified based on their ability to physically prescribe the arterial anatomy as well as the related transport processes. A four-layer porous wall model is then used to investigate the macromolecule transport within an artery and a comprehensive analytical solution is presented. The transport within the lumen and the arterial wall are coupled. The layers are all treated as macroscopically homogeneous porous media. The volume-averaged porous media equations are employed to solve for transport through the porous arterial layers. Staverman filtration coefficient is incorporated to account for selective permeability of each porous layer to macromolecules. The problem encompasses complex interfacial transport phenomena involving various porous-porous as well as porous-fluid interfaces. The method of matched asymptotic expansions is employed to solve for the fluid flow field and species concentration distributions.;Another important aspect of arterial transport is related to aorta-iliac bifurcation. Anatomical studies show that the geometry of aorta-iliac bifurcation is generally asymmetric. Also, statistical data reveal differences in the structural features of average male and female aorta-iliac bifurcation. In the present work, numerical simulations of the macromolecule transport at the aorta-iliac bifurcation are performed. The transport phenomena within the lumen and the arterial wall are coupled. The arterial wall is modeled as a four-layer porous wall, representing endothelium, intima, internal elastic lamina (IEL), and media layers. Different geometrical attributes of the aorta-iliac bifurcation are studied, i.e. asymmetry and gender-dependence. Profiles of macromolecule concentration distributions are obtained for different cases. The results are discussed with regard to the shear stress distribution, which is believed to be one of the key factors in atherogenesis. In addition, discrete modeling of the progression of atherosclerosis is investigated with respect to the wall shear stress and macromolecule transport. The effects of inflammation of one branch on the hemodynamics and macromolecule of the other branch is also discussed.;Drug-eluting vascular stents have shown a great potential in controlling the atherosclerotic complications. However, due to their complex geometry, their analytical modeling remains inaccurate and their simulations, computationally expensive. In the present work, mathematical analysis and numerical simulations of the mass transport in a drug-eluting stent is performed. The latticed structure of the drug-eluting vascular stent is modeled as a porous medium and porous media theory is used to obtain its morphological properties such as permeability and effective diffusivity. Our analytical results, which are based on porous media theory, are compared with those obtained from numerical simulation of mass transport in latticed drug-eluting vascular stents.;As a side, we have also analyzed the transport phenomena within Polymer electrolyte membrane (PEM) fuel cells due to the importance role of porous media in these devices.