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https://www.readbyqxmd.com/read/28547013/new-cfd-tools-to-evaluate-nasal-airflow
#1
M A Burgos, E Sanmiguel-Rojas, C Del Pino, M A Sevilla-García, F Esteban-Ortega
Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. As currently CFD is not a usual tool for rhinologists, a group of engineers in collaboration with experts in Rhinology have developed a very intuitive CFD software. The program MECOMLAND(®) only required snapshots from the patient's cross-sectional (tomographic) images, being the output those results originated by CFD, such as airflow distributions, velocity profiles, pressure, temperature, or wall shear stress. This is useful complementary information to cover diagnosis, prognosis, or follow-up of nasal pathologies based on quantitative magnitudes linked to airflow...
May 25, 2017: European Archives of Oto-rhino-laryngology
https://www.readbyqxmd.com/read/28544511/computational-fluid-dynamics-evaluation-of-posterior-septectomy-as-a-viable-treatment-option-for-large-septal-perforations
#2
Bradley A Otto, Chengyu Li, Alexander A Farag, Benjamin Bush, Jillian P Krebs, Ryan D Hutcheson, Kanghyun Kim, Bhakthi Deshpande, Kai Zhao
BACKGROUND: Numerous surgical techniques exist to treat nasal septal perforation (NSP). The surgical closure of large NSPs (>2 cm) is still challenging. Posterior septectomy has been reported as a simple alternative to treat large NSP, yet its mechanisms for symptom relief are not clear, and if failed, its consequence cannot be easily reversed. METHODS: Ten NSP patients were recruited: 5 underwent posterior septectomy and 5 underwent conventional flap or button repair...
May 23, 2017: International Forum of Allergy & Rhinology
https://www.readbyqxmd.com/read/28542193/an-agent-based-model-of-leukocyte-transendothelial-migration-during-atherogenesis
#3
Rita Bhui, Heather N Hayenga
A vast amount of work has been dedicated to the effects of hemodynamics and cytokines on leukocyte adhesion and trans-endothelial migration (TEM) and subsequent accumulation of leukocyte-derived foam cells in the artery wall. However, a comprehensive mechanobiological model to capture these spatiotemporal events and predict the growth and remodeling of an atherosclerotic artery is still lacking. Here, we present a multiscale model of leukocyte TEM and plaque evolution in the left anterior descending (LAD) coronary artery...
May 2017: PLoS Computational Biology
https://www.readbyqxmd.com/read/28535909/dynamic-simulation-and-doppler-ultrasonography-validation-of-blood-flow-behavior-in-abdominal-aortic-aneurysm
#4
Cristian C Botar, Árpád Á Tóth, Olivera R Klisurić, Dijana D Nićiforović, Viktorija A Vučaj Ćirilović, Viktor E Till
Criteria for rupture prediction of Abdominal Aortic Aneurysm (AAA) are based only on the diameter of AAA. This method does not consider complex hemodynamic forces exerted on AAA wall. The methodology used in our study combines Computer-Aided Design (CAD) with Computational Fluid Dynamics (CFD). Three-dimensional vascular structures reconstructions were based on Computed Tomography (CT) images and CAD. CFD theory was used for mathematical modeling and simulations. In this way, dynamic behavior of blood flow in bounded three-dimensional space was described...
May 2017: Physica Medica: PM
https://www.readbyqxmd.com/read/28525548/computational-fluid-dynamics-characterization-of-pulsatile-flow-in-central-and-sano-shunts-connected-to-the-pulmonary-arteries-importance-of-graft-angulation-on-shear-stress-induced-platelet-mediated-thrombosis
#5
Robert Ascuitto, Nancy Ross-Ascuitto, Martin Guillot, Carey Celestin
OBJECTIVES: Central (aorta) and Sano (right ventricle)-to-pulmonary artery (PA) shunts, palliative operations for infants with complex heart defects, can develop life-threatening thrombosis. We employed computational fluid dynamics (CFD) to study pulsatile flow in these shunts, with the goal to identify haemodynamic characteristics conducive to thrombus formation. METHODS: CFD, using the finite volume method with cardiac catheterization data, and computer simulations, based on angiography, were employed to determine flow-velocity field, wall shear stress (WSS) profile and oscillatory shear index (OSI)...
May 19, 2017: Interactive Cardiovascular and Thoracic Surgery
https://www.readbyqxmd.com/read/28523829/the-prediction-of-viscous-losses-and-pressure-drop-in-models-of-the-human-airways
#6
A K Wells, I P Jones, S Hamill, R Bordas
This paper examines the viscous flow resistance in branching tubes as applied to simplified models of the lungs, and compares the results of Computational Fluid Dynamics (CFD) simulations for a range of conditions with measurement data. The results are in good agreement with the available measurement data for both inspiration and expiration. A detailed sensitivity analysis of the dissipation and viscous resistance in a branch then examines the ratio of the viscous resistance to that for a fully developed Poiseuille flow, Z...
May 18, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28515570/association-between-hemodynamic-modifications-and-clinical-outcome-of-intracranial-aneurysms-treated-using-flow-diverters
#7
Nikhil Paliwal, Robert J Damiano, Jason M Davies, Adnan H Siddiqui, Hui Meng
Treatment of intracranial aneurysms (IAs) has been revolutionized by the advent of endovascular Flow Diverters (FDs), which disrupt blood flow within the aneurysm to induce pro-thrombotic conditions, and serves as a scaffold for endothelial ingrowth and arterial remodeling. Despite good clinical success of FDs, complications like incomplete occlusion and post-treatment rupture leading to subarachnoid hemorrhage have been reported. In silico computational fluid dynamic analysis of the pre- and post-treated geometries of IA patients can shed light on the contrasting blood hemodynamics associated with different clinical outcomes...
February 11, 2017: Proceedings of SPIE
https://www.readbyqxmd.com/read/28515420/vascular-remodelling-relates-to-an-elevated-oscillatory-shear-index-and-relative-residence-time-in-spontaneously-hypertensive-rats
#8
Zhiyan Chen, Haiyi Yu, Yue Shi, Minjia Zhu, Yueshen Wang, Xi Hu, Youyi Zhang, Yu Chang, Ming Xu, Wei Gao
Haemodynamic disorders are common clinical findings in hypertension and lead to adverse cardiovascular events. However, the haemodynamic conditions in hypertension models are poorly understood. This study aimed to observe the characteristics of haemodynamics in spontaneously hypertensive rats (SHRs) and antihypertensive-treated SHRs. Twenty-four adult male SHRs and Wistar-Kyoto rats (WKYs) were randomly divided into four groups and treated for 7 days as follows: WKY-CON (WKYs + saline), WKY-NIF (WKYs + nifedipine, 50 mg/kg/day), SHR-CON (SHRs + saline), and SHR-NIF (SHRs + nifedipine)...
May 17, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28512709/influence-of-low-temperature-combustion-and-dimethyl-ether-diesel-blends-on-performance-combustion-and-emission-characteristics-of-common-rail-diesel-engine-a-cfd-study
#9
Venkatesh Tavareppa Lamani, Ajay Kumar Yadav, Kumar Gottekere Narayanappa
Due to presence of more oxygen, absence of carbon-carbon (C-C) bond in chemical structure, and high cetane number of dimethyl ether (DME), pollution from DME operated engine is less compared to diesel engine. Hence, the DME can be a promising alternative fuel for diesel engine. The present study emphasizes the effect of various exhaust gas recirculation (EGR) rates (0-20%) and DME/Diesel blends (0-20%) on combustion characteristics and exhaust emissions of common rail direct injection (CRDI) engine using three-dimensional computational fluid dynamics (CFD) simulation...
May 16, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28506222/computational-fluid-dynamics-study-of-intra-arterial-chemotherapy-for-oral-cancer
#10
Hiroaki Kitajima, Marie Oshima, Toshinori Iwai, Yoshihito Ohhara, Yasuharu Yajima, Kenji Mitsudo, Iwai Tohnai
BACKGROUND: Intra-arterial chemotherapy (IAC) for oral cancer can deliver a higher concentration of anticancer agent into a tumor-feeding artery than intravenous systemic chemotherapy. However, distribution of anticancer agent into several branches of the external carotid artery (ECA) in IAC has not demonstrated sufficient treatment efficacy. To improve the effectiveness of IAC, the flow distribution of anticancer agent into the branches of the ECA in several IAC methods was investigated using computational fluid dynamics (CFD)...
May 15, 2017: Biomedical Engineering Online
https://www.readbyqxmd.com/read/28500311/optimisation-of-a-novel-spiral-inducing-bypass-graft-using-computational-fluid-dynamics
#11
Andres Ruiz-Soler, Foad Kabinejadian, Mark A Slevin, Paulo J Bartolo, Amir Keshmiri
Graft failure is currently a major concern for medical practitioners in treating Peripheral Vascular Disease (PVD) and Coronary Artery Disease (CAD). It is now widely accepted that unfavourable haemodynamic conditions play an essential role in the formation and development of intimal hyperplasia, which is the main cause of graft failure. This paper uses Computational Fluid Dynamics (CFD) to conduct a parametric study to enhance the design and performance of a novel prosthetic graft, which utilises internal ridge(s) to induce spiral flow...
May 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28494383/a-robust-construction-algorithm-of-the-centerline-skeleton-for-complex-aortic-vascular-structure-using-computational-fluid-dynamics
#12
Julien Touati, Marco Bologna, Adeline Schwein, Francesco Migliavacca, Marc Garbey
Centerlines of blood vessels are useful tools to make important anatomical measurements (length, diameter, area), which cannot be accurately obtained using 2D images. In this paper a brand new method for centerline extraction of vascular trees is presented. By using computational fluid dynamics (CFD) we are able to obtain a robust and purely functional centerline allowing us to support better measurements than classic purely geometrical-based centerlines. We show that the CFD-based centerline is within a few pixels from the geometrical centerline where the latter is defined (far away from inlet/outlets and from the branches)...
April 29, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28488441/multiscale-studies-on-ionic-liquids
#13
Kun Dong, Xiaomin Liu, Haifeng Dong, Xiangping Zhang, Suojiang Zhang
Ionic liquids (ILs) offer a wide range of promising applications because of their much enhanced properties. However, further development of such materials depends on the fundamental understanding of their hierarchical structures and behaviors, which requires multiscale strategies to provide coupling among various length scales. In this review, we first introduce the structures and properties of these typical ILs. Then, we introduce the multiscale modeling methods that have been applied to the ILs, covering from molecular scale (QM/MM), to mesoscale (CG, DPD), to macroscale (CFD for unit scale and thermodynamics COSMO-RS model and environmental assessment GD method for process scale)...
May 24, 2017: Chemical Reviews
https://www.readbyqxmd.com/read/28481722/ems-provider-perceptions-on-termination-of-resuscitation-in-a-large-urban-ems-system
#14
Katie L Tataris, Christopher T Richards, Leslee Stein-Spencer, Stephanie Ryan, Pete Lazzara, Joseph M Weber
OBJECTIVE: Despite the value of out-of-hospital Termination of Resuscitation (TOR) and the scientific evidence in favor of this practice, TOR has not been uniformly adopted or consistently practiced in EMS systems. Previous focus group studies have identified multiple barriers to implementation of out of hospital TOR but existing literature on EMS provider perceptions is limited. We sought to identify EMS providers' perceived barriers to performing out-of-hospital TOR in a large urban EMS system...
May 8, 2017: Prehospital Emergency Care
https://www.readbyqxmd.com/read/28479438/computational-fluid-dynamic-analysis-after-carotid-endarterectomy-patch-graft-versus-direct-suture-closure
#15
Maurizio Domanin, Adelaide Buora, Francesco Scardulla, Bruno Guerciotti, Laura Forzenigo, Pietro Biondetti, Christian Vergara
BACKGROUND: Closure tecnique after carotid endarterectomy (CEA) still remains an issue of debate. Routinely use of patch graft (PG) has been advocated to reduce restenosis, stroke, and death but its protective effect, particularly from late restenosis, is less evident and recent studies call into question this thesis. OBJECTIVE: This study aims to compare PG and direct suture (DS) by means of computational fluid-dynamic (CFD). To identify carotid regions with flow recirculation more prone to restenosis development, we analyzed time averaged oscillatory shear index (OSI) and relative residence time (RRT), that are well known indices correlated with plaque formation...
May 4, 2017: Annals of Vascular Surgery
https://www.readbyqxmd.com/read/28465404/does-the-dsa-reconstruction-kernel-affect-hemodynamic-predictions-in-intracranial-aneurysms-an-analysis-of-geometry-and-blood-flow-variations
#16
P Berg, S Saalfeld, S Voß, T Redel, B Preim, G Janiga, O Beuing
BACKGROUND: Computational fluid dynamics (CFD) blood flow predictions in intracranial aneurysms promise great potential to reveal patient-specific flow structures. Since the workflow from image acquisition to the final result includes various processing steps, quantifications of the individual introduced potential error sources are required. METHODS: Three-dimensional (3D) reconstruction of the acquired imaging data as input to 3D model generation was evaluated...
May 2, 2017: Journal of Neurointerventional Surgery
https://www.readbyqxmd.com/read/28462417/non-uniform-moving-boundary-method-for-cfd-simulation-of-intrathecal-cerebrospinal-flow-distribution-in-a-cynomolgus-monkey
#17
Mohammadreza Khani, Tao Xing, Christina Gibbs, John Oshinski, Gregory R Stewart, Jillynne R Zeller, Bryn A Martin
A detailed quantification and understanding of cerebrospinal fluid (CSF) dynamics may improve detection and treatment of central nervous system (CNS) diseases and help optimize CSF system-based delivery of CNS therapeutics. This study presents a computational fluid dynamics (CFD) model that utilizes a non-uniform moving boundary approach to accurately reproduce the non-uniform distribution of CSF flow along the spinal subarachnoid space (SAS) of a single cynomolgus monkey. A magnetic resonance imaging (MRI) protocol was developed and applied to quantify subject-specific CSF space geometry and flow and define the CFD domain and boundary conditions...
May 2, 2017: Journal of Biomechanical Engineering
https://www.readbyqxmd.com/read/28457722/lower-pressure-heating-steam-is-practical-for-the-distributed-dry-dilute-sulfuric-acid-pretreatment
#18
Shuai Shao, Jian Zhang, Weiliang Hou, Abdul Sattar Qureshi, Jie Bao
Most studies paid more attention to the pretreatment temperature and the resulted pretreatment efficiency, while ignored the heating media and their scalability to an industry scale. This study aimed to use a relative low pressure heating steam easily provided by steam boiler to meet the requirement of distributed dry dilute acid pretreatment. The results showed that the physical properties of the pretreated corn stover were maintained stable using the steam pressure varying from 1.5, 1.7, 1.9 to 2.1MPa. Enzymatic hydrolysis and high solids loading simultaneous saccharification and fermentation (SSF) results were also satisfying...
April 20, 2017: Bioresource Technology
https://www.readbyqxmd.com/read/28457427/blood-flow-velocity-prediction-in-aorto-iliac-stent-grafts-using-computational-fluid-dynamics-and-taguchi-method
#19
Albert Y Chong, Barry J Doyle, Shirley Jansen, Stefan Ponosh, Julien Cisonni, Zhonghua Sun
Covered Endovascular Reconstruction of Aortic Bifurcation (CERAB) is a new technique to treat extensive aortoiliac occlusive disease with covered expandable stent grafts to rebuild the aortoiliac bifurcation. Post stenting Doppler ultrasound (DUS) measurement of maximum peak systolic velocity (PSVmax) in the stented segment is widely used to determine patency and for follow up surveillance due to the portability, affordability and ease of use. Anecdotally, changes in hemodynamics created by CERAB can lead to falsely high PSVmax requiring CT angiography (CTA) for further assessment...
May 1, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28453933/computational-fluid-dynamics-studies-of-a-flow-reactor-free-energies-of-clusters-of-sulfuric-acid-with-nh3-or-dimethyl-amine
#20
D R Hanson, I Bier, B Panta, C N Jen, P H McMurry
Computational fluid dynamics simulations of a flow reactor provided 3D spatial distributions of its temperature and flow profiles and abundances of sulfuric acid, nitrogeneous base, and the acid-base clusters formed from them. Clusters were simulated via their kinetic formation and decomposition involving sulfuric acid and base molecules. Temperature and flow profiles and the base and sulfuric acid distributions are characterized and the latter is compared to mass spectrometer measurements. Concentrations of simulated clusters of sulfuric acid with either NH3 or dimethylamine were compared to experimentally measured particle concentrations...
May 10, 2017: Journal of Physical Chemistry. A
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