Oscillatory flows of viscoelastic fluids are studied from the perspective of Stokes viscoelastic layers. We identify the governing dimensionless variables, and study the flows in a general way for fluids with linear rheology. Nonlinearities can be treated perturbatively to account for reported flow instabilities. This article is part of the theme issue 'Stokes at 200 (Part 1)'.
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http://dx.doi.org/10.1098/rsta.2019.0521 | DOI Listing |
Innovations (Phila)
December 2024
Department of Neurosciences and Rehabilitation, Cardiac Surgery Unit, University of Ferrara, Italy.
Objective: Both the en bloc island technique and the branched graft technique (BGT) present advantages but also limitations in aortic arch surgery. Here is the first presentation of an innovative prosthesis for aortic arch replacement, conceived to overcome the disadvantages of both techniques.
Methods: The novel ISLAND graft is a tubular Dacron or hybrid prosthesis with an additional extended Dacron graft ("bubble") on the superior aspect, for en bloc island graft anastomosis.
Micromachines (Basel)
December 2024
Department of Cardiovascular Medicine, Heart, Vascular & Thoracic Institute, Cleveland Clinic, Cleveland, OH 44195, USA.
Inferior vena cava (IVC) filters are vital in preventing pulmonary embolism (PE) by trapping large blood clots, especially in patients unsuitable for anticoagulation. In this study, the accuracy of two common simplifying assumptions in numerical studies of IVC filters-the rigid wall assumption and the laminar flow model-is examined, contrasting them with more realistic hyperelastic wall and turbulent flow models. Using fluid-structure interaction (FSI) and computational fluid dynamics (CFD) techniques, the investigation focuses on three hemodynamic parameters: time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and relative residence time (RRT).
View Article and Find Full Text PDFJ Neurosurg
January 2025
1Department of Bioengineering, George Mason University, Fairfax, Virginia.
Objective: The complex mix of factors, including hemodynamic forces and wall remodeling mechanisms, that drive intracranial aneurysm growth is unclear. This study focuses on the specific regions within aneurysm walls where growth occurs and their relationship to the prevalent hemodynamic conditions to reveal critical mechanisms leading to enlargement.
Methods: The authors examined hemodynamic models of 67 longitudinally followed aneurysms, identifying 88 growth regions.
Sci Adv
January 2025
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
Symmetrical wave ripples identified with NASA's Curiosity rover in ancient lake deposits at Gale crater provide a key paleoclimate constraint for early Mars: At the time of ripple formation, climate conditions must have supported ice-free liquid water on the surface of Mars. These features are the most definitive examples of wave ripples on another planet. The ripples occur in two stratigraphic intervals within the orbitally defined Layered Sulfate Unit: a thin but laterally extensive unit at the base of the Amapari member of the Mirador formation, and a sandstone lens within the Contigo member of the Mirador formation.
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
Qingdao Sunefire Science & Technology Shares Co., Ltd, Qingdao 266423, China.
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