FSI Based Fundarmental Research On The Hemodynamic Model With Transmission Load And Biomechanical Behaviors Of Aneurism

In recent years, with the improvement of attention on cardiovascular diseases, hemodynamic have developed into a significant research field of biomechanics researches. In patient-specific researches which are based on CT and MRI, hemodynamic are widely used in diagnoses of aneurysms and other diseases. In order to provide the theoretical basis and references for these researches, and to create a computing platform to study multifactorial diseases, it is needed to build a more complete hemodynamic model. As for the aspect of construction of human body, the heart is the source of flow, the blood vessels are transporting pipes and capillaries are the load of the circulatory system. There is strong Fluid-Structure interaction effect in the arterial flow, and interactions between different physiologic structures are existed. So intensive researches of the properties and interactions of arteries are necessary, and the combinatorial method of hemodynamic model should be explored.Therefore, based on the fundamental theory of hydrodynamics, intensive researches on FSI pipe with transmission load under physiological parameters are conducted by means of computational fluid dynamics methods. Based on the results of these researches, the method to build a more complete hemodynamic model was established and a human circulatory system model was built. Finally, studies on the thoracic and abdominal aortic aneurysm were conducted under this model to reveal the formation principles.The main research contents and innovative points of this paper are as follows:(1) On the basis of ALE method and Darcy porous media model, we built a liquid-solid-porous media seepage coupling model. Numerous numerical simulations proved that the complex coupling relationships among fluid solid and porous media seepage are existed.(2) Based on the liquid-solid-porous media seepage coupling model, researches under different wall elastic modulus were conducted to reveal the fundamental form of FSI effects. It was proved that the blood pressure amplitude is decided by the pressure wave velocity. And the pressure wave propagation determined the space-time distribution of pressure. Then further researches of the superposition of pressure and reflected pressure were conducted.(3) Based on the liquid-solid-porous media seepage coupling model, researches under different resistances were conducted to reveal the fundamental form of resistance effects. The numerical simulation results showed that a critical resistance exist in the flow field. And further studies pointed out that Young’s modulus and flow cycle can influence this critical resistance. And the energy transport property affected the flow.(4) Based on the properties of the pressure wave, similarity parameter of temporal distribution(Pf) and similarity parameter of geometry deformation(Psc) were established, and simulation results proved the reasonability of them. On the basis of the researches of transmission load, the principle of the storing, releasing and consumption of the energy was established in the pipe flow. Based on the conservation of energy, a deduce method of the flow resistance was built, and simulation results verified the reasonability of it. Then based on these two theories, the method to build a more complete hemodynamic model was established and a human circulatory system model was built. Numerical simulation results showed that this model was reliable and reasonable.(5) Based on the human circulatory system model, numerical researches on the thoracic and abdominal aortic aneurysm were conducted to reveal the formation principles. In the researches of thoracic aortic aneurysm, result showed that lower Young’s modulus of descending aorta brought the lower level of blood pressure and Von Mises stress, and reduced the wall shear stress, which increase the risk of atherosclerosis. In the researches of thoracic aortic aneurysm, result showed that arteriosclerosis on arteria crural is and other branch arteries brought the higher level of blood pressure and Von Mises stress, and reduced the wall shear stress, which increase the risk of atherosclerosis.