Tetrahedral vs. polyhedral mesh size evaluation on flow velocity and wall shear stress for cerebral hemodynamic simulation

Abstract

Haemodynamic factors, in particular wall shear stresses (WSSs) may have significant impact on growth and rupture of cerebral aneurysms. Without a means to measure WSS reliably in vivo, computational fluid dynamic (CFD) simulations are frequently employed to visualise and quantify blood flow from patient-specific computational models. With increasing interest in integrating these CFD simulations into pretreatment planning, a better understanding of the validity of the calculations in respect to computation parameters such as volume element type, mesh size and mesh composition is needed. In this study, CFD results for the two most common aneurysm types (saccular and terminal) are compared for polyhedral- vs. tetrahedral-based meshes and discussed regarding future clinical applications. For this purpose, a set of models were constructed for each aneurysm with spatially varying surface and volume mesh configurations (mesh size range: 5119-258, 481 volume elements). WSS distribution on the model wall and point-based velocity measurements were compared for each configuration model. Our results indicate a benefit of polyhedral meshes in respect to convergence speed and more homogeneous WSS patterns. Computational variations of WSS values and blood velocities are between 0.84 and 6.3% from the most simple mesh (tetrahedral elements only) and the most advanced mesh design investigated (polyhedral mesh with boundary layer).

Longitudinal computational fluid dynamics study of aneurysmal dilatation in a chronic DeBakey type III aortic dissection

“…Distributions of total pressure, here the force per unit area exerted by the blood flow perpendicular to the aortic wall, and wall sheer stress, which is the force per unit area exerted by the blood flow parallel to or along the aortic wall, were determined in a volume of interest defined at the posterior thoracic false lumen wall (the location of largest dilatation). Further technical details can be found in the Appendix (online only 3,5 ).…”

Computational Fluid Dynamics for the Assessment of Cerebrospinal Fluid Flow and Its Coupling with Cerebral Blood Flow

“…Prismatic buffer elements are also used in conjunction with otherwise tetrahedral grids in boundary layer areas, where high velocity gradients need to be resolved. Less common but emerging are polyhedral grids that can be generated with the same level of automation as tetrahedral grids, while offering more accurate solutions [16].…”

Polyhedral meshing as an innovative approach to computational domain discretization of a cyclone in a fluidized bed CLC unit

“…Advances in aerospace [11], automotive [12], civil engineering [13], medicine [14] and other numerous branches of industry could not have been achieved without applying numerical modelling as a research tool. The primary and critical activity in numerical modelling is the computational domain discretization.…”