The principal investigator and his colleagues use an experiment-based computational approach to model blood flow in large stenotic arteries and investigate critical flow and artery wall behaviors that may lead to artery compression, plaque cap rupture, stroke and heart attack. Dynamic properties of the stenotic arteries with plaque stiffness and geometry variations are determined experimentally using hydrogel tubes whose mechanical properties are close to those of bovine carotid arteries. This leads to a series of 3-D nonlinear computational models with fluid-wall interactions based on the experimental measurements. Arbitrary Lagrangian-Eulerian formulation is used to deal with free moving boundaries. Implicit methods including the SIMPLER algorithm and fully coupled methods based on mesh-free generalized finite differences with staggered grids, upwind techniques, and a consistent physical interpolation technique are used to solve the fluid model. A sequence of experiment-based thin- and thick-wall models are introduced to model the dynamic nonlinear properties of the stenotic tube wall with large strain, deformation, compression and collapse. An incremental boundary iteration method and an under-relaxation technique are used to handle the fluid-wall interactions. Validated by experimental data, results obtained are physiologically relevant and may provide information helpful for early detection, diagnosis and prevention of related cardiovascular diseases. The models and numerical methods developed are applicable to a wide range of problems with fluid-structure interactions and can be extended to include mass transfer, structures of arteries and plaques, endothelial responses, and arterial remodeling. Stenosis, a constriction in blood vessels, is one of the leading causes of death in the western world. The investigators and their colleagues couple experiments with computations to model blood flow in large stenotic arteries and investigate critical flow and artery wall behaviors that may lead to artery compression, plaque cap rupture, stroke and heart attack. The problem is difficult because of the high complexity of artery structure and its nonlinear mechanical properties, strong blood and artery interactions, and critical flow conditions caused by severe stenosis. Dynamic properties of the stenotic arteries are determined experimentally using bovine carotid arteries and hydrogel tubes, whose properties are close to those of bovine carotid arteries. A series of 3-D nonlinear computational models with fluid-wall interactions, based on the experimental measurements, are solved by a novel numerical method to quantify conditions under which artery compression and plaque cap rupture may occur. Validated by experimental data, these results can be helpful for early detection, diagnosis and prevention of related cardiovascular diseases. The models and numerical methods developed are applicable to a wide range of problems with fluid-structure interactions and complex geometries. The models can be extended to include mass transfer, structures of arteries and plaques, grafts and stents, endothelial responses and arterial remodeling. As applications of biotechnology, the results obtained can be used to improve the design of medical devices such as grafts and stents.
