Numerical Simulation Of Hemodynamics In Portal Vein System

The severity of portal hypertension determines the occurrence of many kinds of complications.Portal vein thrombosis is a common complication in patients with portal hypertension.Transjugular intrahepatic portosystemic shunt could reduce portal pressure from the root cause by establishing a shunt between the hepatic vein and the portal vein.It is an effective method to solve a variety of portal hypertension complications including portal vein thrombosis.Based on the CFD software,this article was used Euler two-fluid model to simulate and analyzed the influence of different stent parameters and thrombosis obstruction degree on the flow field characteristics of the portal venous system,providing a theoretical basis for the clinical diagnosis and treatment of portal hypertension and its complications..The main research contents of this article are as follows:（1）This article introduces the development of using CFD to study the portal venous system by domestic and foreign scholars,and compares the results of Euler two-fluid model with fluid-solid coupling model,pure flow field model and the experimental results of Chen Bin et al,to verify the accuracy and feasibility of the model.In addition,an improved method for calculating the proportion of blood in the stent from SMV through the Euler two-fluid model is proposed for the first time.（2）This article studies the influence of inlet velocity and stent parameters on the flow field characteristics of normal portal vein system.The larger the stent diameter（D）and inlet velocity,the smaller the stent angle（α）and stent placement position（L）,the greater the hypotensive effect of the stent.The proportion of blood in the stent from SMV increases with the decrease of the stent diameter（D）,the increase of the stent placement position（L）and the increase of the inlet velocity,and it firstly increases and then decreases as the stent angle（α）increases.The larger the stent diameter（D）,the smaller the evaluation function F of the final result.When the stent angle（α）is≥30°,the larger the stent placement position（L）is,the smaller the F value is.When the stent angle（α）is≤45°,the larger the stent angle（α）is,the smaller the F value is.（3）Based on the normal portal vein system and considering the presence of thrombus,the influence of inlet velocity,stent parameters and degree of thrombus obstruction（K）on the flow field characteristics of the system was studied.The greater the degree of obstruction,inlet velocity and stent diameter（D）,the smaller the stent angle（α）and placement position（L）,the greater the hypotensive effect of the stent.The larger the degree of obstruction（K）,the stent diameter（D）,the stent placement position（L）,and the inlet velocity,the greater the proportion of blood from SMV in the stent,and the Q₁/Q_SMV firstly increased and then decreased with the increase of the stent angle（α）.The larger the obstruction degree（K）and inlet velocity,the larger the F value.