In this work, we present a scalable and efficient parallel solver for the partitioned solution of fluid–structure interaction problems through multi-code coupling. Two instances of an in-house parallel software, TermoFluids, are used to solve the fluid and the structural sub-problems, coupled together on the interface via the preCICE coupling library. For fluid flow, the Arbitrary Lagrangian–Eulerian form of the Navier–Stokes equations is solved on an unstructured conforming grid using a second-order finite-volume discretization. A parallel dynamic mesh method for unstructured meshes is used to track the moving boundary. For the structural problem, the nonlinear elastodynamics equations are solved on an unstructured grid using a second-order finite-volume method. A semi-implicit FSI coupling method is used which segregates the fluid pressure term and couples it strongly to the structure, while the remaining fluid terms and the geometrical nonlinearities are only loosely coupled. A robust and advanced multi-vector quasi-Newton method is used for the coupling iterations between the solvers. Both the fluid and the structural solver use distributed-memory parallelism. The intra-solver communication required for data update in the solution process is carried out using non-blocking point-to-point communicators. The inter-code communication is fully parallel and point-to-point, avoiding any central communication unit. Inside each single-physics solver, the load is balanced by dividing the computational domain into fairly equal blocks for each process. Additionally, a load balancing model is used at the inter-code level to minimize the overall idle time of the processes. Two practical test cases in the context of hemodynamics are studied, demonstrating the accuracy and computational efficiency of the coupled solver. Strong scalability test results show a parallel efficiency of 83% on 10,080 CPU cores.

中文翻译：

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流固耦合问题分区解的可扩展框架

在这项工作中，我们通过多代码耦合为流固耦合问题的分区解决方案提供了一种可扩展且高效的并行求解器。内部并行软件 TermoFluids 的两个实例用于解决流体和结构子问题，它们通过 preCICE 耦合库在接口上耦合在一起。对于流体流动，Navier-Stokes 方程的任意拉格朗日-欧拉形式使用二阶有限体积离散化在非结构化一致网格上求解。非结构化网格的并行动态网格方法用于跟踪移动边界。对于结构问题，非线性弹性动力学方程使用二阶有限体积法在非结构化网格上求解。使用半隐式 FSI 耦合方法分离流体压力项并将其与结构强耦合，而其余流体项和几何非线性仅松散耦合。求解器之间的耦合迭代使用了强大且先进的多向量拟牛顿法。流体和结构求解器都使用分布式内存并行。求解过程中数据更新所需的求解器内部通信是使用非阻塞点对点通信器进行的。码间通信是完全并行和点对点的，避免了任何中央通信单元。在每个单物理场求解器中，通过将计算域划分为每个进程的相当相等的块来平衡负载。此外，在代码间级别使用负载平衡模型来最小化进程的整体空闲时间。研究了血液动力学背景下的两个实际测试案例，证明了耦合求解器的准确性和计算效率。强大的可扩展性测试结果显示，在 10,080 个 CPU 内核上的并行效率为 83%。