Computation of Two-Dimensional Stokes Flows via Lightning and AAA Rational Approximation

SIAM Journal on Scientific Computing, Год журнала: 2024, Номер 46(2), С. A1214 - A1234

Опубликована: Апрель 3, 2024

.Low Reynolds number fluid flows are governed by the Stokes equations. In two dimensions, can be described analytic functions, known as Goursat functions. Brubeck and Trefethen [SIAM J. Sci. Comput., 44 (2022), pp. A1205–A1226] recently introduced a lightning solver that uses rational functions to approximate in polygonal domains. this paper, we present LARS algorithm (lightning-AAA Stokes) for computing two-dimensional (2D) domains with smooth boundaries multiply connected using AAA approximation [Y. Nakatsukasa, O. Sète, L. N. Trefethen, SIAM 40 (2018), A1494–A1522]. After validating our against analytical solutions, solve variety of 2D flow problems physical engineering applications. Using these examples, show now used compute general The computations take less than second give solutions at least 6-digit accuracy.Reproducibility computational results.This paper has been awarded "SIAM Reproducibility Badge: Code data available" recognition authors have followed reproducibility principles valued SISC scientific community. allow readers reproduce results available https://github.com/YidanXue/LARS supplementary materials (128848_2_supp_551755_s5tk4s.zip [15.4KB]).KeywordsStokes flowbiharmonic equationlightning solverAAA algorithmrational approximationMSC codes41A2065N3576D07

Язык: Английский

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Stokes flows in a two-dimensional bifurcation

Royal Society Open Science, Год журнала: 2025, Номер 12(1)

Опубликована: Янв. 1, 2025

The flow network model is an established approach to approximate pressure–flow relationships in a bifurcating network, and has been widely used many contexts. Existing models typically assume unidirectional exploit Poiseuille’s law, thus neglect the impact of bifurcation geometry finite-sized objects on flow. We determine by computing Stokes flows two-dimensional (2D) using Lightning-AAA Rational algorithm, novel mesh-free algorithm for solving 2D problems utilizing applied complex analysis based rational approximation Goursat functions. compute conductances bifurcations with different channel widths, angles, curved boundary geometries fixed circular objects. quantify difference between computed their Poiseuille law approximations demonstrate importance incorporating detailed into existing models. parametrize as functions dimensionless parameters object machine learning approach, which simple use provides more accurate than law. Finally, details are presented.

Язык: Английский

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Modelling midline shift and ventricle collapse in cerebral oedema following acute ischaemic stroke

PLoS Computational Biology, Год журнала: 2024, Номер 20(5), С. e1012145 - e1012145

Опубликована: Май 28, 2024

In ischaemic stroke, a large reduction in blood supply can lead to the breakdown of blood-brain barrier and cerebral oedema after reperfusion therapy. The resulting fluid accumulation brain may contribute significant rise intracranial pressure (ICP) tissue deformation. Changes level ICP are essential for clinical decision-making therapeutic strategies. However, measurement is constrained by techniques obtaining exact values has proven challenging. this study, we propose first computational model simulation following acute stroke investigation midline shift (MLS) relationship. consists three components healthy flow, occluded flow oedema, respectively. utilized obtain core geometry then imported into growth. results compared with data from 97 traumatic injury patients validation major parameters. Midline been widely used diagnosis, decision-making, prognosis patients. Therefore, focus on quantifying relationship between identify factors that affect ICP-MLS Three investigated, including geometry, damage severity types (including rare oedema). Meanwhile, two (stress tension/compression) mechanical also presented differences stress, tension, compression intraparenchymal periventricular regions discussed. This work helps predict precisely therefore provides improved guidance treatment oedema.

Язык: Английский

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A pathogenic role for IL-10 signalling in capillary stalling and cognitive impairment in type 1 diabetes

Nature Metabolism, Год журнала: 2024, Номер 6(11), С. 2082 - 2099

Опубликована: Ноя. 4, 2024

Vascular pathology is associated with cognitive impairment in diseases such as type 1 diabetes; however, how capillary flow affected and the underlying mechanisms remain elusive. Here we show that capillaries diabetic mouse brain both sexes are prone to stalling, blocks consisting primarily of erythrocytes branches off ascending venules. Screening for circulating inflammatory cytokines revealed persistently high levels interleukin-10 (IL-10) mice. Contrary expectation, stimulating IL-10 signalling increased obstruction, whereas inhibiting receptors neutralizing antibodies or endothelial specific knockdown mice reversed these impairments. Chronic treatment receptor improved cerebral blood flow, flux diameter, downregulated haemostasis cell adhesion-related gene expression, deficits. These data suggest has an unexpected pathogenic role microcirculatory defects diabetes. Interleukin-10 promotes formation a model

Язык: Английский

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Arterial arcades and collaterals regress under hemodynamics-based diameter adaptation: A computational and mathematical analysis

Journal of Theoretical Biology, Год журнала: 2025, Номер unknown, С. 112111 - 112111

Опубликована: Апрель 1, 2025

Язык: Английский

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From hypoxic pockets to daily routines: linking brain oxygenation and cognitive resilience

Frontiers in Aging Neuroscience, Год журнала: 2025, Номер 17

Опубликована: Янв. 29, 2025

The discovery of hypoxic pockets within the cortical regions has transformed understanding cerebral oxygen dynamics, revealing their dual role as both contributors to neuronal adaptation and potential precursors dysfunction. These transient oxygen-deprived microenvironments play a pivotal in neurovascular coupling, synaptic plasticity, angiogenesis, processes crucial for maintaining cognitive resilience health. Investigating is particularly relevant aging populations individuals with neurodegenerative conditions. Concurrently, research underscores ability physical, social, activities modulate brain oxygenation, offering natural, accessible interventions optimize delivery utilization. This study synthesizes findings from neuroimaging, behavioral science, longitudinal studies, illustrating how daily routines can mitigate hypoxia-induced decline promote resilience. By integrating insights centenarians, hypoxia-adapted species, multimodal intervention this framework highlights transformative lifestyle-based strategies addressing deficits. advocate an interdisciplinary approach develop targeted public health, rehabilitation, personalized care.

Язык: Английский

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Transit time mean and variance are markers of vascular network structure, wall shear stress distribution and oxygen extraction fraction

Biomechanics and Modeling in Mechanobiology, Год журнала: 2025, Номер unknown

Опубликована: Май 27, 2025

Язык: Английский

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Review of in silico models of cerebral blood flow in health and pathology

Progress in Biomedical Engineering, Год журнала: 2023, Номер 5(2), С. 022003 - 022003

Опубликована: Апрель 1, 2023

Abstract In this review, we provide a summary of the state-of-the-art in silico modelling cerebral blood flow (CBF) and its application clinical trials. CBF plays key role transport nutrients, including oxygen glucose, to brain cells, vasculature is highly complex, multi-scale, dynamic system that acts ensure supply demand these nutrients are continuously balanced. It also other substances, such as recombinant tissue-plasminogen activator, tissue. Any dysfunction can rapidly lead cell death permanent damage regions, leading loss bodily functions death. The complexity difficulty obtaining accurate anatomical information combine make mathematical models understanding supply, diagnosis cerebrovascular disease, quantification effects thrombi, selection optimum intervention, neurosurgical planning. Similar have now been widely applied variety body organs (most notably heart), but still far behind. increased availability experimental data last 15 years however has enabled develop more progress focus review. We thus present brief review foundations underpin both microvasculature macrovasculature. demonstrate how be context diseases show work recently expanded trials for first time. Most date performed ischaemic stroke or aneurysms, in-silico many applications neurodegenerative where vital play testing hypotheses providing test beds interventions.

Язык: Английский

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Human whole-brain models of cerebral blood flow and oxygen transport

Brain Multiphysics, Год журнала: 2023, Номер 5, С. 100083 - 100083

Опубликована: Окт. 6, 2023

The cerebral vasculature plays a critical role in the transport of oxygen and other nutrients to brain tissue. However, size, complexity, paucity detailed anatomical information this system makes understanding behaviour normal pathological conditions, as well its response stimuli, highly challenging. Whole-brain mathematical models have valuable play measurement parameters. for same reasons, whole-brain are complex construct. In study, we propose novel multi-compartment approach blood flow transport. Building on prior models, new formulation based multiple compartment porous medium approach. Using non-dimensional analysis, derive most compact form equations constrain parameter space using clinically measurable quantities, such baseline perfusion volume. We illustrate spatially temporally varying by simulating changes both arterial pressure saturation, showing that is strongly dependent upon depth, with large but slow responses being found deep small fast nearer surface, whereas very rapid comparison. Blood oxygenation thus shown exhibit different characteristic time scales. This has significant implications how consider external autoregulation reactivity responses, model at

Язык: Английский

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Perivascular clearance of blood proteins after blood-brain barrier disruption in a rat model of microinfarcts

Microvascular Research, Год журнала: 2023, Номер 148, С. 104515 - 104515

Опубликована: Март 7, 2023

Microinfarcts result in a transient loss of the blood-brain barrier (BBB) ischemic territory. This leads to extravasation blood proteins into brain parenchyma. It is not clear how these are removed. Here we studied role perivascular spaces clearance from extravasated proteins. Male and female Wistar rats were infused with microspheres either 15, 25, or 50 μm diameter (n = 6 per group) via left carotid artery. We 25,000 15 μm, 5500 25 1000 μm. One day later, lectin hypoxyprobe label perfused vessels hypoxic areas, respectively. Rats then euthanized perfusion-fixed. Brains excised, sectioned, analyzed using immunostaining confocal imaging. Microspheres induced size-dependent increase volume territory, but cumulative was similar all groups. The total volumes ischemia, hypoxia infarction affected 1-2 % hemisphere. Immunoglobulins (IgG) present tissue surrounding lodged In addition, staining for IgG found nearby areas BBB disruption. About 2/3 arteries, while remaining 1/3 veins. subarachnoid space (SAS) hemisphere stained stronger than contralateral groups: +27 %, +44 various sizes induce local integrity, evidenced by parenchymal staining. presence both arteries veins distinct territories suggests that contribute removal strong SAS this route egresses CSF. Perivascular therefore play previously unrecognized fluid after disruption microinfarcts.

Язык: Английский

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