Numerical Study Of Hemodynamics In Pulmonary Artery Stenosis

The incidence rate of vascular diseases such as pulmonary artery stenosis is increasing year by year,and its numerical simulation has also become a key project of biomedical engineering.In previous studies,there have been few studies on the hemodynamics of pulmonary artery stenosis due to a large number of pulmonary artery branches,complex structures,and a small number of samples.In addition,in previous studies,the stenosis site is a simplified model,and the physiological structure of the narrow site model is rarely analyzed.In recent years,the rapid development of computational technology and medical imaging has laid the foundation for the numerical study of noninvasive pulmonary artery stenosis.Duing to the increasing number of pulmonary artery stenosis and other diseases,it is of great significance to study the hemodynamic characteristics of pulmonary artery stenosis by means of computational fluid dynamics.From the current situation of numerical research on pulmonary stenosis,it is found that there are few studies on the four pulmonary artery branches and stenosis site models.Based on this research situation,this paper focuses on the establishment of idealized model and individual model to simulate the hemodynamic changes of pulmonary artery stenosis model,and explore the mechanical properties between blood flow and vascular wall caused by stenosis.The main contents of the study are as follows:1.An idealized model of pulmonary artery stenosis is constructed based on human pulmonary angiography,which is mainly divided into the main pulmonary artery,left and right pulmonary arteries,and their branches.The governing equation,boundary conditions and computational conditions of blood flow are given in this paper.The computational fluid dynamics analysis is carried out through fluid-structure coupling,and then the simulation results are obtained.The hemodynamic data results are analyzed.Based on the idealized model,the variation trends of pressure,velocity,and wall shear stress under Newtonian fluid simulation are studied and analyzed.The guiding significance of hemodynamics for clinical diagnosis and treatment is discussed.The influence of laminar model and turbulent model on hemodynamics is discussed,and this study provids the basis for the subsequent hemodynamics numerical study of pulmonary artery solid model.At the same time,the effects of different degrees of stenosis on hemodynamics and quantitative pulmonary pressure ratios are compared.The findings reveal a considerable disparity in pressure between the two extremities of the stenosis,a high rate of flow and a high wall shear stress at its center,with the wall shear stress at the distal end gradually diminishing.In the comparative analysis of numerical studies of laminar and turbulent models,the numerical results of turbulent models are relatively large.In addition,as the degree of stenosis increases,the quantitative pulmonary artery pressure ratio gradually decreases.The numerical results of the idealized model indicate that the computational study of pulmonary arterial hemodynamic parameters can be used for noninvasive diagnosis and treatment of pulmonary vascular diseases in clinical practice.To some extent,this study can help doctors formulate diagnosis and treatment plans in advance and improve prognosis.2.Based on the simulation theory of idealized models,the research on individualized modeling of pulmonary artery stenosis is divided into two parts.The first is to make a personalized anatomical analysis of the medical images.Based on the Computed Tomography data of the patient,the pulmonary artery stenosis model is constructed through the processing of the medical imaging software.The second is to construct a numerical simulation of hemodynamics based on the reconstruction model.Based on clinical analysis of the shape of pulmonary arteriography stenosis,the use of porous media to simulate the stenosis site is proposed.Based on the individualized model,the variation trends of blood flow velocity,pressure,and wall shear stress under Newtonian fluid simulation are analyzed,and the clinical significance of hemodynamics is discussed.The variation trends of hemodynamic parameters and quantitative changes in pulmonary artery pressure ratio under Newtonian fluid simulation and non-Newtonian fluid simulation are compared and analyzed.The results showed that in the presence of stenosis,the blood flow velocity and wall shear stress in the artery are higher,exceeding the normal physiological range.The quantitative pulmonary pressure ratio simulated by non-Newtonian fluid is closer to the real clinical value.This analysis confirmed that the stenosis model of porous media simulation is of clinical reference significance,and non-Newtonian fluid simulation of blood flow is more convincing,which provides a quantitative basis for clinical diagnosis and treatment.In the numerical work of individualized pulmonary artery stenosis model,it is more meaningful to use porous media model to simulate the stenosis site.