An efficient parallel simulation of unsteady blood flows in patient‐specific pulmonary artery

Self Cite

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.

Section: Numerical Experiments and Observationsmentioning

confidence: 63%

Section: Numerical Experiments and Observationsmentioning

confidence: 63%

Simulation of unsteady blood flows in a patient‐specific compliant pulmonary artery with a highly parallel monolithically coupled fluid‐structure interaction algorithm

Kong

Kheyfets

Finol

et al. 2019

Self Cite

“…Here σ = − p I + 2 με ( u ) is the Cauchy stress tensor where I is an 3 × 3 identity matrix and

ε ((), u) = \frac{1}{2} ((), \nabla boldu + \nabla u^{T})

49 . A wall is the total area of the artery wall.…”

Section: Numerical Experimentsmentioning

confidence: 99%

A parallel non‐nested two‐level domain decomposition method for simulating blood flows in cerebral artery of stroke patient

Chen

Cheng

et al. 2020

Self Cite

Numerical simulation of blood flows in patient‐specific arteries can be useful for the understanding of vascular diseases, as well as for surgery planning. In this paper, we simulate blood flows in the full cerebral artery of stroke patients. To accurately resolve the flow in this rather complex geometry with stenosis is challenging and it is also important to obtain the results in a short amount of computing time so that the simulation can be used in pre‐ and/or post‐surgery planning. For this purpose, we introduce a highly scalable, parallel non‐nested two‐level domain decomposition method for the three‐dimensional unsteady incompressible Navier‐Stokes equations with an impedance outlet boundary condition. The problem is discretized with a stabilized finite element method on unstructured meshes in space and a fully implicit method in time, and the large nonlinear systems are solved by a preconditioned parallel Newton‐Krylov method with a two‐level Schwarz method. The key component of the method is a non‐nested coarse problem solved using a subset of processor cores and its solution is interpolated to the fine space using radial basis functions. To validate and verify the proposed algorithm and its highly parallel implementation, we consider a case with available clinical data and show that the computed result matches with the measured data. Further numerical experiments indicate that the proposed method works well for realistic geometry and parameters of a full size cerebral artery of an adult stroke patient on a supercomputers with thousands of processor cores.

“…There are several recent publications devoted to the development of parallel algorithms for blood flow simulations. For example, Kong et al 16 developed a scalable parallel domain decomposition method to investigate an unsteady blood flow problem that works well on a supercomputer with up to 10,000 processor cores. Later, Kong et al 5 extended the method to solve a monolithically coupled fluid–structure system for the modeling the interaction of blood flow and arterial wall in a patient‐specific compliant pulmonary artery.…”

Section: Introductionmentioning

confidence: 99%

“…In this work, we study an efficient and highly parallel finite element method based on domain decomposition method for the Navier–Stokes equations 5,16,19‐21 . With the method, a simulation of a full 3D patient‐specific hepatic flow on a mesh with around 10 million elements can be accomplished in a few hours.…”

Section: Introductionmentioning

confidence: 99%

A highly parallel simulation of patient‐specific hepatic flows

Lin

Chen

Gao

et al. 2021

Self Cite

Computational hemodynamics is being developed as an alternative approach for assisting clinical diagnosis and treatment planning for liver diseases. The technology is non‐invasive, but the computational time could be high when the full geometry of the blood vessels is taken into account. Existing approaches use either one‐dimensional model of the artery or simplified three‐dimensional tubular geometry in order to reduce the computational time, but the accuracy is sometime compromised, for example, when simulating blood flows in arteries with plaque. In this work, we study a highly parallel method for the transient incompressible Navier–Stokes equations for the simulation of the blood flows in the full three‐dimensional patient‐specific hepatic artery, portal vein and hepatic vein. As applications, we also simulate the flow in a patient with hepatectomy and calculate the S (PPG). One of the advantages of simulating blood flows in all hepatic vessels is that it provides a direct estimate of the PPG, which is a gold standard value to assess the portal hypertension. Moreover, the robustness and scalability of the algorithm are also investigated. A 83% parallel efficiency is achieved for solving a problem with 7 million elements on a supercomputer with more than 1000 processor cores.