The nested block preconditioning technique for the incompressible Navier–Stokes equations with emphasis on hemodynamic simulations
Computer Methods in Applied Mechanics and Engineering
View details for DOI 10.1016/j.cma.2020.113122
Integrated Image-Based Computational Fluid Dynamics Modeling Software as an Instructional Tool.
Journal of biomechanical engineering
Computational modeling of cardiovascular flows is becoming increasingly important in a range of biomedical applications, and understanding the fundamentals of computational modeling is important for engineering students. In addition to their purpose as research tools, integrated image-based computational fluid dynamics platforms can be used to teach the fundamental principles involved in computational modeling and generate interest in studying cardiovascular disease. We report the results of a study performed at five institutions designed to investigate the effectiveness of an integrated modeling platform as an instructional tool and describe "best practices" for using an integrated modeling platform in the classroom. Use of an integrated modeling platform as an instructional tool in nontraditional educational settings (workshops, study abroad programs, in outreach) is also discussed. Results of the study show statistically significant improvements in understanding after using the integrated modeling platform, suggesting such platforms can be effective tools for teaching fundamental cardiovascular computational modeling principles.
View details for DOI 10.1115/1.4047479
View details for PubMedID 32529203
Image-based scaling laws for somatic growth and pulmonary artery morphometry from infant- to adulthood.
American journal of physiology. Heart and circulatory physiology
Pulmonary artery (PA) morphometry has been extensively explored in adults, with particular focus on intra-acinar arteries. However, scaling law relationships for length and diameter of extensive pre-acinar PAs by age have not been previously reported for in vivo human data. To understand pre-acinar PA growth spanning children to adults, we performed morphometric analyses of all PAs visible in the computed tomography (CT) and magnetic resonance (MR) images from a healthy subject cohort (n=16; age: 1-51 years; body surface area, BSA: 0.49-2.01 m2). Subject-specific anatomic PA models were constructed from CT and MR images, and morphometric information - diameter, length, tortuosity, bifurcation angle, and connectivity - was extracted and sorted into diameter-defined Strahler orders. Validation of Murray's law, describing optimal scaling exponents of radii for branching vessels, was performed to determine how closely PAs conform to this classical relationship. Using regression analyses of vessel diameters and lengths against orders and patient metrics (BSA, age, height), we found that diameters increased exponentially with order and allometrically with patient metrics, and length increased allometrically with patient metrics, albeit weakly. The average tortuosity index of all vessels was 0.026 ± 0.024, average bifurcation angle was 28.2º ± 15.1º, and average Murray's law exponent was 2.92 ± 1.07. We report a set of scaling laws for vessel diameter and length, along with other morphometric information. These provide an initial understanding of healthy structural pre-acinar PA development with age, which can be used for computational modeling studies and comparison with diseased PA anatomy.
View details for DOI 10.1152/ajpheart.00123.2020
View details for PubMedID 32618514
Evolution of hemodynamic forces in the pulmonary tree with progressively worsening pulmonary arterial hypertension in pediatric patients.
Biomechanics and modeling in mechanobiology
Pulmonary arterial hypertension (PAH) is characterized by pulmonary vascular remodeling resulting in right ventricular (RV) dysfunction and ultimately RV failure. Mechanical stimuli acting on the vessel walls of the full pulmonary tree have not previously been comprehensively characterized. The goal of this study is to characterize wall shear stress (WSS) and strain in pediatric PAH patients at different stages of disease severity using computational patient-specific modeling. Computed tomography, magnetic resonance imaging and right heart catheterization data were collected and assimilated into pulmonary artery (PA) models for patients with and without PAH. Patients were grouped in three disease severity groups (control, moderate and severe) based on clinical evaluations. A finite element solver was employed to quantify hemodynamics and wall strains. To estimate WSS in the distal small PAs with diameters ranging from 50 to 500[Formula: see text], a morphometric tree model was created, with inputs coming from outlets of the 3D model. WSS in the proximal PAs decreased with disease severity (control 20.5 vs. moderate 15.8 vs. severe 6.3[Formula: see text], [Formula: see text]). Oscillatory shear index increased in the main pulmonary artery (MPA) with disease severity (0.13 vs. 0.13 vs. 0.2, [Formula: see text]). Wall strains measured by the first invariant of Green strain tensor decreased with disease severity (0.16 vs. 0.12 vs. 0.11, [Formula: see text]). Mean WSS for the distal PAs between 100 and 500[Formula: see text] significantly increased with disease severity (20 vs. 52 vs. 116 [Formula: see text], [Formula: see text]). In conclusion, 3D flow simulations showed that WSS is significantly decreased in the MPA with disease while the mathematical morphometric model suggested increased WSS in the distal small vessels. Computational models can reveal mechanical stimuli acting on vessel walls that may inform patient risk stratification and flow shear experiments.
View details for PubMedID 30635853