Hemodynamic Simulation Of Aortic Dissection Based On Fluid-structure Interaction

Aortic dissection is a cardiovascular disease caused by a tear in the intima of the aortic wall that allows blood to enter the interior of the aortic wall,creating a new flow channel.Hemodynamic factors have an important influence on the development and treatment of aortic dissection.Numerical hemodynamics simulations are able to provide some important diagnostic and prognostic information for clinical treatment,thus reducing or avoiding surgical risks.Aortic hemodynamic simulation methods have experienced from rigid wall to fluidstructure interaction and from idea model to patient-specific model;however,the complexity of fluid-structure interaction and patient-specific models are significantly higher compared to rigid wall simulation based on the ideal models,and three-dimensional patient-specific fluid-structure interaction simulations are very time consuming and usually need hundreds of hours.In order to simulate the patient-specific three-dimensional aortic dissection problem with high accuracy and efficiency,we introduce a scalable parallel solver to do the simulations on a supercomputer.With the proposed solver it is able to perform accurate and fast blood flow simulations of patient-specific full-size threedimension aortic with dissection.The mathematic model includes time-dependent fluid system with the arbitrary Lagrangian-Eulerian description,structure system with the Lagrangian description,and a moving mesh system.All the three systems are coupled into a fully-coupled system for solution.For the discritization,we use an unstructured grid-based finite element method for the spacial discretization and a fully implicit finite difference method for the temporal discritization.A domain decomposition method based parallel Newton-Krylov-Schwarz method is used to solve the large-scale nonlinear system in each time step.We did a high resolution blood flow simulation of a patient-specific aortic dissection case with realistic geometry and physical parameters,and numerical results show that the flow-structure interaction simulation is able to capture more hemodynamic information than the fluid only simulation,and the pressure,velocity,wall shear stress and displacement are all in a reasonable physiological range.In addition,we tested the parallel scalability of the proposed solver on the Tianhe-2A supercomputer,where the fluid only case achieved 40.25% efficiency with 3840 cores and the fluid-structure interaction simulation achieved 44.15% parallel efficiency with 2304 cores.The proposed solver can do a complete heartbeat cycle fluid-structure interaction simulation of aortic dissection with over 10 million grid cells within one hour,which shows the high potential for clinical applications.