title: Progress in the CFD modeling of flow instabilities in anatomical total cavopulmonary connections.
abstract: Intrinsic flow instability has recently been reported in the blood flow pathways of the surgically created total-cavopulmonary connection. Besides its contribution to the hydrodynamic power loss and hepatic blood mixing, this flow unsteadiness causes enormous challenges in its computational fluid dynamics (CFD) modeling. This paper investigates the applicability of hybrid unstructured meshing and solver options of a commercially available CFD package (FLUENT, ANSYS Inc., NH) to model such complex flows. Two patient-specific anatomies with radically different transient flow dynamics are studied both numerically and experimentally (via unsteady particle image velocimetry and flow visualization). A new unstructured hybrid mesh layout consisting of an internal core of hexahedral elements surrounded by transition layers of tetrahedral elements is employed to mesh the flow domain. The numerical simulations are carried out using the parallelized second-order accurate upwind scheme of FLUENT. The numerical validation is conducted in two stages: first, by comparing the overall flow structures and velocity magnitudes of the numerical and experimental flow fields, and then by comparing the spectral content at different points in the connection. The numerical approach showed good quantitative agreement with experiment, and total simulation time was well within a clinically relevant time-scale of our surgical planning application. It also further establishes the ability to conduct accurate numerical simulations using hybrid unstructured meshes, a format that is attractive if one ever wants to pursue automated flow analysis in a large number of complex (patient-specific) geometries.
authors.affiliation: Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Room 2119 U. A. Whitaker Building, 313 Ferst Dr, Atlanta, GA 30332-0535, USA.
authors.forename: Chang
authors.initials: C
authors.lastname: Wang
authors.forename: Kerem
authors.initials: K
authors.lastname: Pekkan
authors.forename: Diane
authors.initials: D
authors.lastname: de Zélicourt
authors.forename: Marc
authors.initials: M
authors.lastname: Horner
authors.forename: Ajay
authors.initials: A
authors.lastname: Parihar
authors.forename: Ashish
authors.initials: A
authors.lastname: Kulkarni
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Yoganathan
mesh_terms: D001783:Blood Flow Velocity; D002302:Cardiac Output; D003198:Computer Simulation; D018729:Fontan Procedure / Q000379:methods; D018610:Heart Bypass, Right / Q000379:methods*; D006439:Hemodynamics; D006801:Humans; D008955:Models, Cardiovascular; D011651:Pulmonary Artery / Q000502:physiology* / Q000601:surgery*; D015203:Reproducibility of Results; D014684:Venae Cavae / Q000503:physiopathology* / Q000601:surgery*