Characterization of Coherent Structures in the Cardiovascular System
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Recent advances in blood flow modeling have provided highly resolved, four-dimensional data of fluid mechanics in large vessels. The motivation for such modeling is often to better understand how flow conditions relate to health and disease, or to evaluate interventions that affect, or are affected by, blood flow mechanics. Vessel geometry and the pulsatile pumping of blood leads to complex flow, which is often difficult to characterize. This article discusses a computational method to better characterize blood flow kinematics. In particular, we compute Lagrangian coherent structures (LCS) to study flow in large vessels. We demonstrate that LCS can be used to characterize flow stagnation, flow separation, partitioning of fluid to downstream vasculature, and mechanisms governing stirring and mixing in vascular models. This perspective allows valuable understanding of flow features in large vessels beyond methods traditionally considered.
KeywordsHemodynamics Computational fluid dynamics Biofluid mechanics Finite-time Lyapunov exponents Lagrangian coherent structures
The authors would like to sincerely thank Alison Marsden and Adam Bernstein for the TCPC velocity data and Andrea Les for the patient-specific AAA velocity data. The authors gratefully acknowledge the use of the AcuSolve linear algebra package (http://www.acusim.com) and the MeshSim automatic mesh generator (http://www.simmetrix.com). S. Shadden was supported by an NSF Mathematical Sciences Postdoctoral Research Fellowship. This work was also supported by the National Institutes of Health (P50 HL083800, U54 GM072970) and the National Science Foundation under Grant No. 0205741.
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