Stimulated by a recent controversy regarding pressure drops predicted in a giant aneurysm with a proximal stenosis, the present study sought to assess variability in the prediction of pressures and flow by a wide variety of research groups. In phase I, lumen geometry, flow rates, and fluid properties were specified, leaving each research group to choose their solver, discretization, and solution strategies. Variability was assessed by having each group interpolate their results onto a standardized mesh and centerline. For phase II, a physical model of the geometry was constructed, from which pressure and flow rates were measured. Groups repeated their simulations using a geometry reconstructed from a micro-computed tomography (CT) scan of the physical model with the measured flow rates and fluid properties. Phase I results from 25 groups demonstrated remarkable consistency in the pressure patterns, with the majority predicting peak systolic pressure drops within 8% of each other. Aneurysm sac flow patterns were more variable with only a few groups reporting peak systolic flow instabilities owing to their use of high temporal resolutions. Variability for phase II was comparable, and the median predicted pressure drops were within a few millimeters of mercury of the measured values but only after accounting for submillimeter errors in the reconstruction of the life-sized flow model from micro-CT. In summary, pressure can be predicted with consistency by CFD across a wide range of solvers and solution strategies, but this may not hold true for specific flow patterns or derived quantities. Future challenges are needed and should focus on hemodynamic quantities thought to be of clinical interest.
ascending aorta, the aortic arch, and the descending aorta.Ascending aorta extends upward from the aortic root to the point where the innominate artery branches off the aorta, and the aorta begins to form an arch.Aortic arch represents the curved portion at the top of the aorta.Descending aorta begins just beyond the arch as the aorta bends down into the body.It carries and distributes oxygen rich blood to all arteries.
Previous numerical studies based on 2D coronary artery bypass graft (CABG) model for the optimization of anastomosis configuration has indicated that large graft-host diameter ratio and small junction angle has better hemodynamics. The validity of representing a 3D CABG model with a 2D CABG model is not clear. Four different 3D CABG models and one 2D CABG model were constructed, and their hemodynamics were analyzed and compared in the present study in order to verify this validity. Hemodynamics of the five CABG models were numerically simulated using commercial software ANSYS 9.0. The results showed that the distribution of flow patterns, wall shear stresses and wall shear stress gradients in the 2D model and 3D models were not significantly different. Large or same diameter of graft compared with that of the parent artery, and small suture angle is profitable in clinical application from the point of view of hemodynamics. It can be concluded that the conclusions drawn from the optimization of 2D CABG model is credible and can be used for reference; it is feasible to simplify a 3D CABG model to a 2D model for hemodynamics analysis.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
