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In Silico Evaluation of a Self-powered Venous Ejector Pump for Fontan Patients

CARDIOVASCULAR ENGINEERING AND TECHNOLOGY 2023年第3期14卷 428-446页

作者： Rasooli, Reza Giljarhus, Knut Erik Teigen Hiorth, Aksel Jolma, Ingunn Westvik Vinningland, Jan Ludvig de Lange, Charlotte Brun, Henrik Holmstrom, Henrik Univ Stavanger Fac Sci & Technol Dept Energy Resources N-4036 Stavanger Norway Univ Stavanger Dept Mech & Struct Engn & Mat Sci N-4036 Stavanger Norway Univ Stavanger Dept Chem Biosci & Environm Engn N-4036 Stavanger Norway Norwegian Res Ctr NORCE Oslo Norway Sahlgrens Univ Hosp Dept Paediat Radiol Gothenburg Sweden Oslo Univ Hosp Intervent Ctr Sect Med Cybernet & Image Proc Rikshospitalet Oslo Norway Oslo Univ Hosp Dept Paediat Cardiol Div Paediat & Adolescent Med Oslo Norway Univ Oslo Inst Clin Med Fac Med Oslo Norway

PurposeThe Fontan circulation carries a dismal prognosis in the long term due to its peculiar physiology and lack of a subpulmonic ventricle. Although it is multifactorial, elevated IVC pressure is accepted to be the primary cause of Fontan's high mortality and morbidity. This study presents a self-powered venous ejector pump (VEP) that can be used to lower the high IVC venous pressure in single-ventricle *** self-powered venous assist device that exploits the high-energy aortic flow to lower IVC pressure is designed. The proposed design is clinically feasible, simple in structure, and is powered intracorporeally. The device's performance in reducing IVC pressure is assessed by conducting comprehensive computational fluid dynamics simulations in idealized total cavopulmonary connections with different offsets. The device was finally applied to complex 3D reconstructed patient-specific TCPC models to validate its *** assist device provided a significant IVC pressure drop of more than 3.2 mm Hg in both idealized and patient-specific geometries, while maintaining a high systemic oxygen saturation of more than 90%. The simulations revealed no significant caval pressure rise (< 0.1 mm Hg) and sufficient systemic oxygen saturation (> 84%) in the event of device failure, demonstrating its fail-safe *** self-powered venous assist with promising in silico performance in improving Fontan hemodynamics is proposed. Due to its passive nature, the device has the potential to provide palliation for the growing population of patients with failing Fontan.

关键词： Congenital heart disease Single-ventricle physiology Fontan hemodynamics Systemic venous hypertension computational fluid dynamics Fontan venous assist

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Numerical analysis of different cardiac functions and support modes on blood damage potential in an axial pump

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INTERNATIONAL JOURNAL OF ARTIFICIAL ORGANS 2023年第4期46卷 215-225页

作者： Li, Shulei Jin, Donghai Gui, Xingmin Liu, Guangmao Jiang, Xihang Beihang Univ Sch Energy & Power Engn Beijing Peoples R China Chinese Acad Med Sci & Peking Union Med Coll Fuwai Hosp Natl Ctr Cardiovasc Dis Beijing Peoples R China Beijing Power Machinery Res Inst Beijing Peoples R China Beihang Univ Sch Energy & Power Engn 37 Xueyuan Rd Beijing 100191 Peoples R China

Background: Cardiac functions and support modes of left ventricular assist device (LVAD) will influence the pump inner flow field and blood damage ***: computational fluid dynamics (CFD) method and lumped-parameter-model (LPM) were applied to investigate the impacts of cardiac functions under full (9000 rpm) and partial (8000 rpm) support modes in an axial ***: The constitution of hemolysis index (HI) in different components of the pump was investigated. HI was found to be more sensitive to positive incidence angles (i) compared with negative incidence angles in rotors. Negative incidence angles had little impact on HI both in rotors and the outlet guide vanes. The improved cardiac function made only a minor difference in HIave (estimated average HI in one cardiac cycle) by 9.88%, as the flow rate expanded mainly to higher flow range. Switching to partial support mode, however, would induce a periodic experience of severe flow separation and recirculation at low flow range. This irregular flow field increased HIave by 47.97%, remarkably increasing the blood damage ***: This study revealed the relationship between the blade incidence angle i and HI , and recommended negative-incidence-angle blade designs as it yielded lower HI . Moreover, to avoid flow range below 50% of the design point, careful evaluations should be made before switching support modes as weaning procedures in clinical applications.

关键词： Cardiac function support mode computational fluid dynamics axial pump hemolysis index

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Uneven wear behavior of downhole tool clearance material under slurry erosion

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ALEXANDRIA ENGINEERING JOURNAL 2023年 73卷 47-68页

作者： Liu, Lu Wang, Yu Zhang, Kai Kong, Lingrong China Univ Geosci Sch Engn & Technol Key Lab Deep GeoDrilling Technol Minist Nat Resources Beijing 100083 Peoples R China China Univ Geosci Sch Engn & Technol Beijing 100083 Peoples R China

Slurry erosion of clearance fits is one of the primary reasons for the decline in the per-formance of downhole tools. In this study, slurry erosion experiments and computational fluid dynamics simulations were performed to understand the effect of particle impact velocity as well as the erosion mechanisms on the surface of 38CrMoAlA steel. The results indicated that uneven erosive wear occurred along the flow direction on the surface of clearance material. The uneven ero-sive wear can be attributed to the variation of particle impact angle affected by fluid streamlines. The site and the area of the most severe erosion changed arising from the particle impact velocity. The failure of the clearance material was mainly due to the aggravation of localized erosion wear. To extend the service life of downhole tools, the region downstream of the clearance inlet (10 mm from the inlet) should be prioritized.(c) 2023 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://***/ licenses/by-nc-nd/4.0/).

关键词： Uneven erosion wear computational fluid dynamics Particle impact angle Clearance materials Localized erosion

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Statistical shape representation of the thoracic aorta: accounting for major branches of the aortic arch

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COMPUTER METHODS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING 2023年第13期26卷 1557-1571页

作者： Wiputra, Hadi Matsumoto, Shion Wagenseil, Jessica E. Braverman, Alan C. Voeller, Rochus K. Barocas, Victor H. Univ Minnesota Dept Biomed Engn Minneapolis MN 55455 USA Univ Michigan Dept Biomed Engn Ann Arbor MI 48109 USA Washington Univ Dept Mech Engn & Mat Sci St Louis MO 63110 USA Washington Univ Sch Med Dept Med Cardiovasc Div St Louis MO 63110 USA Univ Minnesota Dept Surg Box 242 UMHC Minneapolis MN 55455 USA

Statistical shape modeling (SSM) is an emerging tool for risk assessment of thoracic aortic aneurysm. However, the head branches of the aortic arch are often excluded in SSM. We introduced an SSM strategy based on principal component analysis that accounts for aortic branches and applied it to a set of patient scans. computational fluid dynamics were performed on the reconstructed geometries to identify the extent to which branch model accuracy affects the calculated wall shear stress (WSS) and pressure. Surface-averaged and location-specific values of pressure did not change significantly, but local WSS error was high near branches when inaccurately modeled.

关键词： Thoracic aorta statistical shape modeling computational fluid dynamics

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Applicability of S-ducts for electric cars: A CFD investigation

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JOURNAL OF ENGINEERING-JOE 2025年第1期2025卷

作者： Callinan, John Boyle, Fergal J. Technol Univ Dublin Sch Mech Engn Dublin Ireland

The switch to electric vehicles has been necessitated by the global warming crisis. One of the primary barriers to the uptake of electric cars is battery range. Much work is ongoing in improving the battery performance to increase range. A more sustainable solution to increase the battery range is to reduce the car's power demands. Drag is one of the primary consumers of vehicle power, particularly for vehicles travelling at higher speeds. It has been shown that a minor reduction in the drag coefficient can result in a significant reduction in the power being consumed. To-date, despite the limited use of S-ducts on both road and race cars, there is little publicly available research on their application for road vehicles. This article addresses the gap in research by assessing the viability of S-ducts to reduce the drag coefficient, and thus increase the battery range, of electric cars. A computational fluid dynamics (CFD) analysis is carried out using the realistic DrivAer Estateback model car. A comprehensive numerical model validation is carried out which assesses both mesh density and turbulence models. Following this, five S-ducts are developed using an iterative design process. It is found that a significant reduction in the drag coefficient, and an increase in battery range, can be achieved with the introduction of an S-duct. These findings show that utilising an S-duct can result in substantial savings in charging costs and a reduction in carbon emissions. This research offers recommendations for the future design of, and research into, S-ducts to achieve further gains in battery range.

关键词： battery range computational fluid dynamics drag coefficient S-duct

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Anisotropic Surface Microrollers for Endovascular Navigation: A computational Analysis with a Case Study in Hepatic Perfusion

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ADVANCED THEORY AND SIMULATIONS 2025年

作者： Arslan, Burak Bozuyuk, Ugur Goerguelue, Kivanc Yildiz, Erdost Ozturk, Hakancan Liotta, Lucia Heinemann, Volker Alguel, Hana Sitti, Metin Max Planck Inst Intelligent Syst Phys Intelligence Dept D-70569 Stuttgart Germany Bilkent Univ Mech Engn Dept TR-06800 Ankara Turkiye Tech Univ Munich Comprehens Canc Ctr Ctr TUM TUM Univ Hosp Klinikum Rechts Isar D-81675 Munich Germany Tech Univ Munich TUM Univ Hosp Inst Tumor Metab Klinikum Rechts Isar D-81675 Munich Germany Tech Univ Munich TUM Univ Hosp Med Klin 2 Klinikum Rechts Isar D-81675 Munich Germany LMU Munich Univ Hosp Comprehens Canc Ctr Munich LMU D-81377 Munich Germany Koc Univ Sch Med TR-34450 Istanbul Turkiye Koc Univ Sch Engn TR-34450 Istanbul Turkiye

Magnetic surface microrollers have demonstrated promise as active drug delivery agents for targeted and minimally invasive disease treatment. Specifically, it can be employed in the circulatory system to locally release therapeutic agents at disease sites, minimizing systemic exposure and reducing side effects, particularly in the treatment of diseases like cancer. Previous research indicates that the design and shape of microrollers play a crucial role in safe navigation within blood vessels, with anisotropic microrollers exhibiting superiority due to favorable hydrodynamic interactions with nearby boundaries. In this study, the navigation potential of anisotropic microrollers is investigated in veins, venules, and capillaries through computational fluid dynamics analyses. These results indicate that robust locomotion is only achievable in larger vessels, such as veins. Subsequently, their performance is explored in a clinically relevant scenario - the hepatic circulation toward treating primary liver cancer or metastatic nodes of distant tumors (e.g., pancreatic cancer). computational fluid dynamics analyses using the data from five different patients demonstrate that robust navigation can be achieved with high actuation frequencies. Overall, the findings presented in this study lay a preliminary foundation for the potential future application of surface microrollers in vivo.

关键词： circulatory system computational fluid dynamics medical microrobotics pancreatic cancer surface microrollers

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Numerical studies on detonation wave in hydrogen-fueled pulse detonation combustor with shrouded ejector

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JOURNAL OF THE BRAZILIAN SOCIETY OF MECHANICAL SCIENCES AND ENGINEERING 2023年第2期45卷 1-15页

作者： Debnath, Pinku Pandey, K. M. Natl Inst Technol Agartala Dept Mech Engn Agartala 799046 Tripura India Natl Inst Technol Silchar Dept Mech Engn Silchar 788010 Assam India

The present paper deals with the unsteady compressible (Ma > 0.3) reacting flows of hydrogen-air mixture in pulse detonation combustor. In order to achieve the potential thrust gain from PDE combustor, the shrouded ejector is placed at exit section of detonation tube. In this analysis, core diameter and ejector length effect on vortex generation has been investigated. Furthermore, the propagation of detonation combustion wave is analyzed for three equivalence ratio (ER) of lean, stoichiometric and rich (phi < 1, phi = 1, phi > 1) in multiple pulse time. Not only the reacting flow structure but also the propulsive performance of pulse detonation combustor has been investigated. Moreover, this numerical simulation is carried out to minimize the fuel consumption in instantaneous pulse time for fully developed detonation wave. The eddy dissipation combustion model with a single-step Arrhenius chemical kinetics model is used to simulate the fuel-air reacting mixture in Ansys fluent platform. The contour plot clearly shows formation number of 2.39 has more significance role for vortex core generation with shortest possible time of 0.033 s. The pickup flame propagation speed of 2310 m/s is obtained, and this magnitude is higher than C-J velocity. The result also indicates that minimum pollutant number is released from lean and rich mixture combustion;even, marginal thrust is generated with magnitude of 35 N and 37 N, respectively, from equivalence ratio of phi = 0.64 and phi = 1.4 at pulse time of 0.033 s. Although the maximum pollutant number of 0.0489 is found from phi = 1.0, strong thrust is obtained from stoichiometric H-2-air mixture.

关键词： Shrouded ejector computational fluid dynamics Pulse detonation combustor Vortex Detonation

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Enhancing the NOx and soot emissions reduction benefits of a low compression ratio light duty diesel engine by optimization of piston bowl design

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INTERNATIONAL JOURNAL OF ENGINE RESEARCH 2023年第3期24卷 1251-1270页

作者： Vikraman, V. Anand, K. Ramesh, A. Indian Inst Technol Madras 201 IC Engines Lab Chennai 600036 Tamil Nadu India

In the present work, the benefits of the low compression ratio (LCR) concept on simultaneous reduction of oxides of nitrogen (NOx) and soot emissions could be further enhanced by optimizing the piston bowl design using a 3-dimensional computational fluid dynamics (CFD) tool. A single-cylinder, direct-injection diesel engine was used for the present investigations. In its mass-production version, the engine had a compression ratio (CR) of 18:1 that was considered as the stock CR from which the LCR variants were derived. The initial and unoptimized piston design of the LCR variant with CR of 14:1 was arrived at using an offset bowl geometry from the stock compression ratio variant, and the corresponding benefits were quantified. The NO (nitric oxide) and soot reduction potential of the LCR variant could be further enhanced by adopting a step-by-step optimization procedure focused on the principal parameters of the bowl viz., piston bowl diameter, centre pip depth, reentrancy and bottom profile. Based on numerical investigations, an optimal piston bowl design could be arrived at that can significantly enhance the benefits of the LCR approach on NO and soot emissions. At a reference operating point of 2000 rpm and 40 N-m, by adopting the optimized profile, the NO reduction potential of the LCR variant could be improved from 10.3% to 40.2%. Moreover, the soot reduction potential could also be improved from 79.1% to 84.2%. The benefits of the optimized bowl design were also confirmed by engine dynamometer measurements across the engine's operating speed range. Thus, it can be concluded that optimization of the piston bowl design specific to the LCR variant could enhance the NOx and soot emission benefits that can help diesel engines comply with the stringent emission regulations.

关键词： Diesel engine nitrogen oxide soot low compression ratio piston bowl design computational fluid dynamics

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Study on collision between single coarse particle and wall in viscous media using CFD-DEM

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EUROPEAN JOURNAL OF MECHANICS B-fluidS 2023年 97卷 199-207页

作者： Chen, Lei Wang, Yifan Klemes, Jiri Jaromir Wang, Jin Tao, Wenquan Xi An Jiao Tong Univ Sch Energy & Power Engn Key Lab Thermofluid Sci & Engn MOE Xian 710049 Shaanxi Peoples R China Brno Univ Technol VUT Brno Fac Mech Engn NETME Ctr Sustainable Proc Integrat Lab SPIL Tech 2896-2 Brno 61669 Czech Republic

Collision between particle and wall is common in granular two-phase flow. This study is helpful to optimise flow conveying system, reduce attrition between materials and devices, and improve development of economy. The collision between a single coarse particle (3 mm in diameter) and wall in a viscous media was investigated by Hertz-Mindlin no-slip contact model based on the coupled computational fluid dynamics and discrete element method (CFD-DEM). Effects of impact velocity and viscosity of media on contact processes and contact force are studied in this research. The calculated results from the collision model are consistent with experimental data, and contact velocity and viscosity of media show significant effects on the contact force of particles. With the reduction of the dimensionless number St, the ratio of unloading time to loading time increases significantly.(c) 2022 Elsevier Masson SAS. All rights reserved.

关键词： Particle-wall collision computational fluid dynamics Discrete element method Hertz-Mindlin model Two-phase flow

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Analysis of heat transfer enhancement due to helical static mixing elements inside cooling channels in machine tools

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2023年第5-6期127卷 2273-2285页

作者： Anders, Denis Reinicke, Ulf Baum, Markus Cologne Univ Appl Sci TH Koln Grp Computat Mech & Fluid Dynam Steinmullerallee 1 D-51643 Gummersbach Germany

In this contribution, the effectiveness of helical static mixers in different arrangements and flow configurations/regimes is explored. By means of a thorough numerical analysis, the application limits of helical static mixers for the heat transfer enhancement inside cooling channels of machine tools are provided. The numerical simulations were processed with the commercial finite volume computational fluid dynamics (CFD) code, ANSYS Fluent 2020 R2. This study shows that there exists an optimal range of application for static mixers as heat exchange intensifier depending on the flow speed, the transmitted heat flow and the thermal conductivity of the tool. The investigations of this contribution are restricted to single-phase flow in circular cross-sections and straight channel geometries. As a representative application example for a machine tooling, the cooling of a simple injection mold is investigated. The research carried out reveals that the application of static mixing elements for enhancement of heat transfer is very effective, particularly for fluid flow with low to medium Reynolds numbers, close-contour cooling, high values of heat fluxes, and high thermal conductivity of the tooling material.

关键词： Mold cooling computational fluid dynamics Heat transfer enhancement Static mixers

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