Article
Mathematics
Gerasim V. Krivovichev
Summary: This paper presents a theoretical analysis of the effects of boundary conditions on the solutions of one-dimensional hemodynamics. The study shows that unphysical unbounded solutions can occur when using bounded functions as boundary conditions. The use of a periodic boundary condition leads to the correct behavior of the solution, and an effective Fourier method is proposed for analytical solutions. The obtained results expand the possibilities of using analytical methods in blood-flow simulation and can be valuable for specialists in the field.
Article
Mathematics, Applied
Michal Bathory, Ulisse Stefanelli
Summary: This paper focuses on the weighted inertia-dissipation-energy variational approach for approximating unsteady Leray-Hopf solutions of the incompressible Navier-Stokes system. The method, initiated in a previous study, is extended to non-Newtonian fluids with power-law index r >= 11/5 in three dimensions and large nonhomogeneous data. The paper also discusses the natural boundary conditions that arise from the minimisation, including Navier-slip type conditions at walls and a newly obtained condition at outflows and inflows.
Article
Mathematics
Stephan Gahima, Pedro Diez, Marco Stefanati, Jose Felix Rodriguez Matas, Alberto Garcia-Gonzalez
Summary: This manuscript presents a novel formulation for a linear elastic model of a heterogeneous arterial section undergoing uniform pressure in a quasi-static regime. The novelties are twofold. First, an elastic bed support on the external boundary (elastic bed boundary condition) replaces the classical Dirichlet boundary condition for elastic solids to ensure a solvable problem. Secondly, an unfitted strategy based on the Immersed Boundary (IB) framework is devised to study different geometrical configurations corresponding to different patients. It provides results equivalent to the standard finite elements (FE) with dimensionality reduction.
Article
Multidisciplinary Sciences
Patricia Clement, Marco Castellaro, Thomas W. Okell, David L. Thomas, Pieter Vandemaele, Sara Elgayar, Aaron Oliver-Taylor, Thomas Kirk, Joseph G. Woods, Sjoerd B. Vos, Joost P. A. Kuijer, Eric Achten, Matthias J. P. van Osch, John A. Detre, Hanzhang Lu, David C. Alsop, Michael A. Chappell, Luis Hernandez-Garcia, Jan Petr, Henk J. M. M. Mutsaerts
Summary: ASL-BIDS is a standardized method for ASL data storage that can improve the reproducibility and data sharing of ASL research.
Article
Clinical Neurology
Christian Heitkamp, Laurens Winkelmeier, Jeremy J. J. Heit, Gregory W. W. Albers, Maarten G. G. Lansberg, Max Wintermark, Gabriel Broocks, Noel van Horn, Helge C. C. Kniep, Peter B. B. Sporns, Kamil Zelenak, Jens Fiehler, Tobias D. D. Faizy
Summary: This study aimed to investigate imaging biomarkers associated with unfavorable functional outcomes despite successful recanalization in AIS-LVO patients. The results showed that unfavorable venous outflow (Vo) on admission is a strong predictor of unfavorable functional outcomes in AIS-LVO patients, even with successful recanalization.
EUROPEAN JOURNAL OF NEUROLOGY
(2023)
Article
Thermodynamics
Sandipan Kumar Das
Summary: This study proposes a new method within the BIM framework to handle symmetry, zero normal-velocity gradient and specified pressure boundary conditions. The method is successfully applied to simple Stokes flow problems and shows good agreement with analytical solutions and literature data.
INTERNATIONAL JOURNAL OF NUMERICAL METHODS FOR HEAT & FLUID FLOW
(2023)
Article
Computer Science, Interdisciplinary Applications
Luciano K. Araki, Rafael B. de R. Borges, Nicholas Dicati P. da Silva, Chi-Wang Shu
Summary: WENO schemes are important in modern CFD for capturing unsteady and non-linear phenomena in complex flows. While there are challenges such as non-boundary-conforming issues, the ILW procedure can be used to overcome them. The proposed ILW outflow boundary treatment and WENOtype extrapolation have shown high order and resolution in experiments.
COMPUTERS & FLUIDS
(2022)
Article
Chemistry, Multidisciplinary
Pat R. Vehrs, Chase Blazzard, Hannah C. Hart, Nicole Kasper, Ryan Lacey, Daniela Lopez, Shay Richards, Dennis L. Eggett
Summary: This study measured arterial occlusion pressure (AOP) in the dominant and non-dominant legs of males and females using different cuff inflation protocols. The results showed no significant differences in AOP within or between the legs, or between sexes. AOP measurements were highly reliable, and the choice of cuff inflation protocol was a matter of personal preference. It is important to measure AOP in both limbs to ensure safe and effective use of blood flow restriction (BFR) during exercise.
APPLIED SCIENCES-BASEL
(2023)
Article
Mathematics
Carlo Mantegazza, Matteo Novaga, Alessandra Pluda
Summary: This paper investigates the motion by curvature of networks and proves that the curvature of evolving networks remains bounded under certain conditions, providing a complete description of the evolution of tree-like networks.
JOURNAL FUR DIE REINE UND ANGEWANDTE MATHEMATIK
(2022)
Article
Mechanics
Hangyu Zhu, Chong Pan, Guohua Wang, Yirui Liang, Xiaocang Ji, Jinjun Wang
Summary: Experimental investigation on particle clustering in a particle-laden turbulent boundary layer with moderate frictional Reynolds number (Re-tau = 5500) reveals self-similarity of particle cluster geometries in the log layer, characterized by power law of the probability density functions of cluster areas and y-scaling of their moments. A conceptual model is proposed where particle clusters tend to reside on back ridges of low-momentum attached u-structures, influenced by high-strain from converging sweep-ejection events. Conditional statistics show sand grains with small slip velocities are captured by low-momentum turbulent motions to form clusters.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Biochemical Research Methods
Endrit Pajaziti, Javier Montalt-Tordera, Claudio Capelli, Raphael Sivera, Emilie Sauvage, Michael Quail, Silvia Schievano, Vivek Muthurangu
Summary: This study explores the use of machine learning (ML) to improve the application of computational fluid dynamics (CFD) in clinical settings. By simulating 3000 CFD simulations on synthetically generated aortic shapes, the ML models were able to reproduce conventional CFD results much faster, with a processing time 4000 times faster than traditional methods, and with reasonable accuracy.
PLOS COMPUTATIONAL BIOLOGY
(2023)
Article
Medicine, Research & Experimental
Tom Nagel, Bridget Melton, Gregory J. Grosicki
Summary: Firefighters are at risk of cardiovascular disease, with arterial stiffness being influenced by age and health behaviors. Structured exercise training is needed to improve arterial compliance and reduce the burden of CVD.
MEDICAL HYPOTHESES
(2022)
Article
Radiology, Nuclear Medicine & Medical Imaging
Tine Arts, Jeroen C. W. Siero, Geert Jan Biessels, Jaco J. M. Zwanenburg
Summary: A robust automated method was developed to exclude small perforators affected by ghosting artifacts, showing moderate to good reliability compared to manual censoring. This method can be used for studying cerebral small arteries.
JOURNAL OF MAGNETIC RESONANCE IMAGING
(2021)
Article
Engineering, Aerospace
Yongle Du, Jinsheng Cai
Summary: The study aims to address the ambiguity in defining characteristic wave amplitudes and proposes a new analysis in the frequency and wave number domain to identify these amplitudes in multidimensional space. A more physically reasonable second-order non-reflecting outflow condition in terms of lateral wave number is derived. Numerical experiments are conducted to evaluate the performances of these non-reflecting conditions.
PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART G-JOURNAL OF AEROSPACE ENGINEERING
(2022)
Article
Computer Science, Interdisciplinary Applications
Matthew Dobson, Abdel Kader A. Geraldo
Summary: This paper presents rotating periodic boundary conditions (PBCs) for simulating uniaxial stretching flow (USF) or biaxial stretching flow (BSF) in nonequilibrium molecular dynamics (NEMD). Specialized PBCs are required for such nonequilibrium flows as the simulation box deforms with the background flow. The proposed technique is simpler than previous PBCs developed for general three dimensional flows and offers better minimum lattice spacing properties.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)