Abstract: A computational vascular fluid-structure interaction framework for the simulation of patient-specific cerebral aneurysm configurations is presented. A new approach for the computation of the blood vessel tissue prestress is also described. Simulations of four patient-specific models are carried out, and quantities of hemodynamic interest such as wall shear stress and wall tension are studied to examine the relevance of fluid-structure interaction modeling when compared to the rigid arterial wall assumption. We demonstrate that flexible wall modeling plays an important role in accurate prediction of patient-specific hemodynamics. Discussion of the clinical relevance of our methods and results is provided.
Abstract: CSF flow has been shown to exhibit complex patterns in MR images in both healthy subjects and in patients with Chiari I. Abnormal CSF flow oscillations, according to prevailing opinion, cause syringomyelia and other clinical manifestations that affect some patients with the Chiari I malformation. For this article, we reviewed the literature on PC MR of CSF flow, collected the published CFD studies relevant to CSF flow, and performed flow simulations. PC MR creates cine and still images of CSF flow and measurements of flow velocities. CFD, a technique used to compute flow and pressure in liquid systems, simulates the CSF flow patterns that occur in a specific geometry or anatomy of the SAS and a specific volume of flow. Published PC MR studies show greater peak CSF velocities and more complex flow patterns in patients with Chiari I than in healthy subjects, with synchronous bidirectional flow one of the characteristic markers of pathologic flow. In mathematic models of the SAS created from high-resolution MR images, CFD displays complex CSF flow patterns similar to those shown in PC MR in patients. CFD shows that the pressure and flow patterns vary from level to level in the upper spinal canal and differ between patients with Chiari and healthy volunteers. In models in which elasticity and motion are incorporated, CFD displays CSF pressure waves in the SAS. PC MR and CFD studies to date demonstrate significant alterations of CSF flow and pressure patterns in patients with Chiari I. CSF flow has nonlaminar complex spatial and temporal variations and associated pressure waves and pressure gradients. Additional simulations of CSF flow supplemented by PC MR will lead to better measures for distinguishing pathologic flow abnormalities that cause syringomyelia, headaches, and other clinical manifestations in Chiari I malformations.
Abstract: This chapter concerns the flow of cerebrospinal fluid (CSF) in the subarachnoid space that surrounds the spinal cord. Particular attention is given to abnormal flow and pressure resulting from the Chiari I malformation and its often associated condition syringomyelia. The chapter builds on the software tools described in Chapter 21, and we will compare the Chorin, IPCS and G2 methods. In this chapter, we will also describe how to create meshes with Gmsh.
Abstract: The paper presents strategies for producing Computer Aided Design (CAD) models that
are suitable for Isogeometric Analysis (IGA) . By extending traditional CAD tools slightly, complex
analysis-suitable shell models can be produced. It is shown how trimmed objects can be converted to
untrimmed objects. By comparing analysis results of various modeling techniques including T-splines,
the influence of the modeling concept is analyzed.
Abstract: Isogeometric analysis is a novel technique in Finite Element Analysis. The current
paper discusses simulation in marine applications using isogeometric shell approximations.
