Simulation of unsteady blood flows in a patient-specific compliant pulmonary artery with a highly parallel monolithically coupled fluid-structure interaction algorithm
Simulation of unsteady blood flows in a patient-specific compliant pulmonary artery with a highly parallel monolithically coupled fluid-structure interaction algorithm
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DOI：
10.1002/cnm.3208
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发表时间：
2019-07-01
影响因子：
2.1
通讯作者：
Cai, Xiao-Chuan
中科院分区：
文献类型：
--
作者：
Kong, Fande;Kheyfets, Vitaly;Cai, Xiao-Chuan
计算流体动力学（CFD）越来越多地用于研究患者特定动脉的血流，以了解某些心血管疾病。这些技术在相对简单的问题上工作得很好，但当问题变得困难时需要改进，当(a)几何结构变得复杂（例如，几个分支到一个完整的肺动脉），(b)模型变得更复杂（例如，流体-仅耦合流体-结构相互作用），(c)流体和壁模型都变得高度非线性，(d)我们运行模拟的计算机是一台拥有数万个处理器核心的超级计算机。为了突破CFD在这四个方面的极限，在本文中，我们开发和研究了一种高度并行的算法来求解一个单片耦合流体结构系统，用于模拟血流和动脉壁的相互作用。作为一个案例研究，我们考虑从计算机断层扫描（CT）图像中获得的患者特定的全尺寸肺动脉，并人工添加固定厚度的壁层。流体模型采用不可压缩的Navier-Stokes方程组，壁面模型采用几何非线性弹性方程。据我们所知，这是第一次在没有假设刚性壁的情况下模拟完整肺动脉的不稳定血流。所提出的数值算法和软件在超级计算机上的规模远远超过10000个处理器核，用于解决在空间上用稳定有限元法离散，在时间上用隐式格式离散的涉及数亿未知数的流固耦合问题。
Computational fluid dynamics (CFD) is increasingly used to study blood flows in patient-specific arteries for understanding certain cardiovascular diseases. The techniques work quite well for relatively simple problems but need improvements when the problems become harder when (a) the geometry becomes complex (eg, a few branches to a full pulmonary artery), (b) the model becomes more complex (eg, fluid-only to coupled fluid-structure interaction), (c) both the fluid and wall models become highly nonlinear, and (d) the computer on which we run the simulation is a supercomputer with tens of thousands of processor cores. To push the limit of CFD in all four fronts, in this paper, we develop and study a highly parallel algorithm for solving a monolithically coupled fluid-structure system for the modeling of the interaction of the blood flow and the arterial wall. As a case study, we consider a patient-specific, full size pulmonary artery obtained from computed tomography (CT) images, with an artificially added layer of wall with a fixed thickness. The fluid is modeled with a system of incompressible Navier-Stokes equations, and the wall is modeled by a geometrically nonlinear elasticity equation. As far as we know, this is the first time the unsteady blood flow in a full pulmonary artery is simulated without assuming a rigid wall. The proposed numerical algorithm and software scale well beyond 10 000 processor cores on a supercomputer for solving the fluid-structure interaction problem discretized with a stabilized finite element method in space and an implicit scheme in time involving hundreds of millions of unknowns.