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Computational fluid dynamics

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https://www.readbyqxmd.com/read/28431825/single-subcortical-infarct-pathomechanism-assessed-by-thin-section-computed-tomography-perfusion
#1
Dong Hoon Shin, Ernst Klotz, Eung Yeop Kim
INTRODUCTION: The pathomechanism of a single subcortical infarct (SSI) may be better determined by assessing the perfusion status between parent artery and ischemic lesion. We aimed to compare the classifications into branch atheromatous disease (BAD) versus non-BAD based on diffusion-weighted imaging (DWI) or computed tomography perfusion (CTP), and to test whether a CTP-based classification improves the predicting power for progression in SSI (PSSI) compared to that by DWI. METHODS: We enrolled 109 consecutive patients with SSI examined by whole-supratentorial brain CTP and follow-up DWI...
April 18, 2017: Journal of Stroke and Cerebrovascular Diseases: the Official Journal of National Stroke Association
https://www.readbyqxmd.com/read/28431428/computational-and-in-vitro-experimental-investigation-of-intrathecal-drug-distribution-parametric-study-of-the-effect-of-injection-volume-cerebrospinal-fluid-pulsatility-and-drug-uptake
#2
Kevin M Tangen, Roxanne Leval, Ankit I Mehta, Andreas A Linninger
BACKGROUND: Intrathecal drug delivery is an attractive option to circumvent the blood-brain barrier for pain management through its increased efficacy of pain relief, reduction in adverse side effects, and cost-effectiveness. Unfortunately, there are limited guidelines for physicians to choose infusion or drug pump settings to administer therapeutic doses to specific regions of the spine or the brain. Although empiric trialing of intrathecal drugs is critical to determine the sustained side effects, currently there is no inexpensive in vitro method to guide the selection of spinal drug delivery parameters...
May 2017: Anesthesia and Analgesia
https://www.readbyqxmd.com/read/28424884/principle-and-basic-property-of-the-sequential-flow-pump
#3
Shintaro Hara, Erina Maeno, Xinyang Li, Terumi Yurimoto, Takashi Isoyama, Itsuro Saito, Toshiya Ono, Yusuke Abe
In the emergency care field, early treatment of acute heart or respiratory failure has been a global concern. In severe cases, patients are frequently required to be on an extracorporeal membrane oxygenator (ECMO) life support. To make the ECMO system more compact and portable, we proposed a sequential flow-type centrifugal pump named the sequential flow pump (SFP). In this study, principle and basic properties of this novel blood pump were examined by computational fluid dynamic (CFD) analysis and an experimental model...
April 19, 2017: Journal of Artificial Organs: the Official Journal of the Japanese Society for Artificial Organs
https://www.readbyqxmd.com/read/28424305/numerical-simulation-of-haemodynamics-and-low-density-lipoprotein-transport-in-the-rabbit-aorta-and-their-correlation-with-atherosclerotic-plaque-thickness
#4
Xiaoyin Li, Xiao Liu, Peng Zhang, Chenglong Feng, Anqiang Sun, Hongyan Kang, Xiaoyan Deng, Yubo Fan
Two mechanisms of shear stress and mass transport have been recognized to play an important role in the development of localized atherosclerosis. However, their relationship and roles in atherogenesis are still obscure. It is necessary to investigate quantitatively the correlation among low-density lipoproteins (LDL) transport, haemodynamic parameters and plaque thickness. We simulated blood flow and LDL transport in rabbit aorta using computational fluid dynamics and evaluated plaque thickness in the aorta of a high-fat-diet rabbit...
April 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28422239/electro-osmosis-at-surfactant-laden-liquid-gas-interfaces-beyond-standard-models
#5
Alexia Barbosa De Lima, Laurent Joly
Electro-osmosis (EO) is a powerful tool to manipulate liquids in micro and nanofluidic systems. While EO has been studied extensively at liquid-solid interfaces, the case of liquid-vapor interfaces, found e.g. in foam films and bubbles, remains to be explored. Here we perform molecular dynamics (MD) simulations of EO in a film of aqueous electrolyte covered with fluid layers of ionic surfactants and surrounded by gas. Following the experimental procedure, we compute the zeta potential from the EO velocity, defined as the velocity difference between the middle of the liquid film and the surrounding gas...
April 19, 2017: Soft Matter
https://www.readbyqxmd.com/read/28417585/speckle-variance-optical-coherence-tomography-of-blood-flow-in-the-beating-mouse-embryonic-heart
#6
Olga A Grishina, Shang Wang, Irina V Larina
Efficient separation of blood and cardiac wall in the beating embryonic heart is essential and critical for experiment-based computational modelling and analysis of early-stage cardiac biomechanics. Although speckle variance optical coherence tomography (SV-OCT) relying on calculation of intensity variance over consecutively acquired frames is a powerful approach for segmentation of fluid flow from static tissue, application of this method in the beating embryonic heart remains challenging because moving structures generate SV signal indistinguishable from the blood...
April 18, 2017: Journal of Biophotonics
https://www.readbyqxmd.com/read/28416689/contractile-and-chiral-activities-codetermine-the-helicity-of-swimming-droplet-trajectories
#7
Elsen Tjhung, Michael E Cates, Davide Marenduzzo
Active fluids are a class of nonequilibrium systems where energy is injected into the system continuously by the constituent particles themselves. Many examples, such as bacterial suspensions and actomyosin networks, are intrinsically chiral at a local scale, so that their activity involves torque dipoles alongside the force dipoles usually considered. Although many aspects of active fluids have been studied, the effects of chirality on them are much less known. Here, we study by computer simulation the dynamics of an unstructured droplet of chiral active fluid in three dimensions...
April 17, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28415302/generalized-three-dimensional-lattice-boltzmann-color-gradient-method-for-immiscible-two-phase-pore-scale-imbibition-and-drainage-in-porous-media
#8
Sébastien Leclaire, Andrea Parmigiani, Orestis Malaspinas, Bastien Chopard, Jonas Latt
This article presents a three-dimensional numerical framework for the simulation of fluid-fluid immiscible compounds in complex geometries, based on the multiple-relaxation-time lattice Boltzmann method to model the fluid dynamics and the color-gradient approach to model multicomponent flow interaction. New lattice weights for the lattices D3Q15, D3Q19, and D3Q27 that improve the Galilean invariance of the color-gradient model as well as for modeling the interfacial tension are derived and provided in the Appendix...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415194/migration-of-a-droplet-in-a-cylindrical-tube-in-the-creeping-flow-regime
#9
Binita Nath, Gautam Biswas, Amaresh Dalal, Kirti Chandra Sahu
The migration of a neutrally buoyant droplet in a tube containing another immiscible liquid is investigated numerically in the creeping flow regime. A fully developed velocity profile is imposed at the inlet of the tube. The interface between the two immiscible fluids is captured using a coupled level-set and volume-of-fluid approach. The deformation and breakup dynamics of the droplet are investigated in terms of three dimensionless parameters, namely, the ratio between the radius of the undeformed droplet and the radius of the capillary tube, the viscosity ratio between the dispersed and the continuous phases, and the capillary number that measures the relative importance of the viscous force over the surface tension force...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28414873/influence-of-pharyngeal-airway-respiration-pressure-on-class-ii-mandibular-retrusion-in-children-a-computational-fluid-dynamics-study-of-inspiration-and-expiration
#10
T Iwasaki, H Sato, H Suga, Y Takemoto, E Inada, I Saitoh, K Kakuno, R Kanomi, Y Yamasaki
OBJECTIVES: To examine the influence of negative pressure of the pharyngeal airway on mandibular retraction during inspiration in children with nasal obstruction using the computational fluid dynamics (CFD) method. SETTING AND SAMPLE POPULATION: Sixty-two children were divided into Classes I, II (mandibular retrusion) and III (mandibular protrusion) malocclusion groups. MATERIAL AND METHODS: Cone-beam computed tomography data were used to reconstruct three-dimensional shapes of the nasal and pharyngeal airways...
May 2017: Orthodontics & Craniofacial Research
https://www.readbyqxmd.com/read/28413231/development-of-a-roof-bolter-canopy-air-curtain-for-respirable-dust-control
#11
W R Reed, G J Joy, B Kendall, A Bailey, Y Zheng
Testing of the roof bolter canopy air curtain (CAC) designed by the U.S. National Institute for Occupational Safety and Health (NIOSH) has gone through many iterations, demonstrating successful dust control performance under controlled laboratory conditions. J.H. Fletcher & Co., an original equipment manufacturer of mining equipment, further developed the concept by incorporating it into the design of its roof bolting machines. In the present work, laboratory testing was conducted, showing dust control efficiencies ranging from 17...
January 2017: Mining Engineering
https://www.readbyqxmd.com/read/28412180/computational-fluid-dynamics-study-of-the-pharyngeal-airway-space-before-and-after-mandibular-setback-surgery-in-patients-with-mandibular-prognathism
#12
Y Yajima, M Oshima, T Iwai, H Kitajima, S Omura, I Tohnai
The purpose of this study was to investigate the relationship between the pressure drop in the pharyngeal airway space (ΔPPAS) and the minimum cross-sectional area (minCSA) of the pharyngeal airway before and after mandibular setback surgery using computational fluid dynamics, in order to prevent iatrogenic obstructive sleep apnoea. Eleven patients with mandibular prognathism underwent bilateral sagittal split osteotomy for mandibular setback. Three-dimensional models of the upper airway were reconstructed from preoperative and postoperative computed tomography images, and simulations were performed using computational fluid dynamics...
April 12, 2017: International Journal of Oral and Maxillofacial Surgery
https://www.readbyqxmd.com/read/28407768/a-study-of-noninvasive-fractional-flow-reserve-derived-from-a-simplified-method-based-on-coronary-computed-tomography-angiography-in-suspected-coronary-artery-disease
#13
Changzheng Shi, Dong Zhang, Kunlin Cao, Tao Zhang, Liangping Luo, Xin Liu, Heye Zhang
BACKGROUND: The invasive fractional flow reserve has been considered the gold standard for identifying ischaemia-related stenosis in patients with suspected coronary artery disease. Determining non-invasive FFR based on coronary computed tomographic angiography datasets using computational fluid dynamics tends to be a demanding process. Therefore, the diagnostic performance of a simplified method for the calculation of FFRCTA requires further evaluation. OBJECTIVES: The aim of this study was to investigate the diagnostic performance of FFRCTA calculated based on a simplified method by referring to the invasive FFR in patient-specific coronary arteries and clinical decision-making...
April 14, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28402518/influence-of-coronary-microcirculatory-dysfunction-on-ffr-calculation-based-on-computational-fluid-dynamics
#14
Hernán Mejia-Renteria, Shengxian Tu, Fernando Macaya, Javier Escaned
No abstract text is available yet for this article.
April 10, 2017: European Heart Journal Cardiovascular Imaging
https://www.readbyqxmd.com/read/28394783/cardiac-computed-tomography-for-planning-revascularization-procedures
#15
Maksymilian P Opolski
Coronary computed tomography angiography (coronary CTA) is being increasingly used to detect and rule out coronary artery stenoses. Beyond stenosis detection, the abundance of anatomic, morphologic, and physiological information incorporated from a single one-stop-shop CT study has generated considerable interest in the context of preprocedural planning for coronary revascularization. Specifically, preprocedural CTA data sets can assist interventional cardiologists with selective catheter placement, appropriate guidewire choice, accurate stent size selection, and, most importantly, development of a stepwise revascularization strategy plan...
April 7, 2017: Journal of Thoracic Imaging
https://www.readbyqxmd.com/read/28388164/pair-mobility-functions-for-rigid-spheres-in-concentrated-colloidal-dispersions-stresslet-and-straining-motion-couplings
#16
Yu Su, James W Swan, Roseanna N Zia
Accurate modeling of particle interactions arising from hydrodynamic, entropic, and other microscopic forces is essential to understanding and predicting particle motion and suspension behavior in complex and biological fluids. The long-range nature of hydrodynamic interactions can be particularly challenging to capture. In dilute dispersions, pair-level interactions are sufficient and can be modeled in detail by analytical relations derived by Jeffrey and Onishi [J. Fluid Mech. 139, 261-290 (1984)] and Jeffrey [Phys...
March 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28387372/computational-fluid-dynamics-simulation-of-the-upper-airway-response-to-large-incisor-retraction-in-adult-class-i-bimaxillary-protrusion-patients
#17
Zhe Zheng, Hong Liu, Qi Xu, Wei Wu, Liling Du, Hong Chen, Yiwen Zhang, Dongxu Liu
The changes of the upper airway after large retraction of the incisors in adult class I bimaxillary protrusion patients were assessed mainly focused on the anatomic variation and ignored the functional changes. This study aimed to investigate the changes of the upper airway in adult class I bimaxillary protrusion patients after extraction treatment using the functional images based on computational fluid dynamics (CFD). CFD was implemented after 3D reconstruction based on the CBCT of 30 patients who have completed extraction treatment...
April 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28385882/understanding-angiography-based-aneurysm-flow-fields-through-comparison-with-computational-fluid-dynamics
#18
J R Cebral, F Mut, B J Chung, L Spelle, J Moret, F van Nijnatten, D Ruijters
BACKGROUND AND PURPOSE: Hemodynamics is thought to be an important factor for aneurysm progression and rupture. Our aim was to evaluate whether flow fields reconstructed from dynamic angiography data can be used to realistically represent the main flow structures in intracranial aneurysms. MATERIALS AND METHODS: DSA-based flow reconstructions, obtained during interventional treatment, were compared qualitatively with flow fields obtained from patient-specific computational fluid dynamics models and quantitatively with projections of the computational fluid dynamics fields (by computing a directional similarity of the vector fields) in 15 cerebral aneurysms...
April 6, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28382440/tetralogy-of-fallot-surgical-repair-shunt-configurations-ductus-arteriosus-and-the-circle-of-willis
#19
Senol Piskin, Gozde Unal, Ahmet Arnaz, Tayyar Sarioglu, Kerem Pekkan
In this study, hemodynamic performance of three novel shunt configurations that are considered for the surgical repair of tetralogy of Fallot (TOF) disease are investigated in detail. Clinical experience suggests that the shunt location, connecting angle, and its diameter can influence the post-operative physiology and the neurodevelopment of the neonatal patient. An experimentally validated second order computational fluid dynamics (CFD) solver and a parametric neonatal diseased great artery model that incorporates the ductus arteriosus (DA) and the full patient-specific circle of Willis (CoW) are employed...
April 5, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28381014/aberration-control-in-adaptive-optics-a-numerical-study-of-arbitrarily-deformable-liquid-lenses
#20
N C Lima, K Mishra, F Mugele
By means of numerical simulations, using a computational fluid dynamics software together with an optical ray tracing analysis platform, we show that we can tune various optical aberrations by electrically manipulating the shape of liquid lenses using one hundred individually addressable electrodes. To demonstrate the flexibility of our design, we define electrode patterns based on specific Zernike modes and show that aspherical, cylindrical and decentered shapes of liquid lenses can be produced. Using different voltages, we evaluate the tuning range of spherical aberration (Z11), astigmatism (Z5 and Z6) and coma (Z7), while a hydrostatic pressure is applied to control the average curvature of a microlens with a diameter of 1mm...
March 20, 2017: Optics Express
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