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Study of fluid-structure interaction in a Functionally Graded pH-Sensitive Hydrogel Micro-Valve

INTERNATIONAL JOURNAL OF APPLIED MECHANICS 2020年第5期12卷

作者： Mazaheri, Hashem Ghasemkhani, Amir Sabbaghi, Soroush Bu Ali Sina Univ Dept Mech Engn Hamadan Hamadan Iran

In this work, fluid-structure interaction (FSI) simulations, as well as non-FSI ones, are conducted to study the behavior of a functionally graded (FG) pH-sensitive micro-valve. The FEM analysis of the hydrogel is performed in ABAQUS while the fluid domain is analyzed in ANSYS fluent. To investigate the FSI and FG effects, both FSI and non-FSI simulations are performed for pH-sensitive micro-valve with homogeneous cross-linking distribution beside the FG cases. Two simulation domains are coupled by using a third-party software named MpCCI for both FSI and non-FSI simulations. For the FG hydrogel, linear and exponential property distributions are considered. The obtained results show a significant difference between the FG and homogeneous hydrogel behavior for both simulation methods. Additionally, the results emphasize that FSI consideration has a crucial role in the design of these smart devices. Especially, remarkable difference is observed for the closing pH of the micro-valve as well as the flow-rate diagrams. For example, a leakage is observed in FSI simulations for the closing pH of the non-FSI simulations that indicates the importance of the FSI effect. Finally, the effect of the cross-linking density distribution and the inlet pressure of micro-valve are studied and the results are analyzed.

关键词： pH-sensitive hydrogel micro-valve fluid-structure interaction functionally graded hydrogel

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Reduced-Order Modeling and Experimental Studies of Bilaterally Coupled fluid-structure interaction in Single-Degree-of-Freedom Flapping Wings

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JOURNAL OF VIBRATION AND ACOUSTICS-TRANSACTIONS OF THE ASME 2020年第2期142卷 021012页

作者： Schwab, Ryan K. Reid, Heidi E. Jankauski, Mark Montana State Univ Dept Mech & Ind Engn Bozeman MT 59717 USA

Flapping wings deform under both aerodynamic and inertial forces. However, many flapping wing fluid-structure interaction (FSI) models require significant computational resources which limit their effectiveness for high-dimensional parametric studies. Here, we present a simple bilaterally coupled FSI model for a wing subject to single-degree-of-freedom (SDOF) flapping. The model is reduced-order and can be solved several orders of magnitude faster than direct computational methods. To verify the model experimentally, we construct a SDOF rotation stage and measure basal strain of a flapping wing in-air and in-vacuum. Overall, the derived model estimates wing strain with good accuracy. In-vacuum, the wing has a large 3 omega response when flapping at approximately one-third of its natural frequency due to a superharmonic resonance, where the superharmonic occurs due to the interaction of inertial forces and time-varying centrifugal softening. In-air, this 3 omega response is attenuated significantly as a result of aerodynamic damping, whereas the primary omega response is increased due to aerodynamic loading. These results highlight the importance of (1) bilateral coupling between the fluid and structure, since unilaterally coupled approaches do not adequately describe deformation-induced aerodynamic damping and (2) time-varying stiffness, which generates superharmonics of the flapping frequency in the wing's dynamic response. The simple SDOF model and experimental study presented in this work demonstrate the potential for a reduced-order FSI model that considers both bilateral fluid-structure coupling and realistic multi-degrees-of-freedom flapping kinematics moving forward.

关键词： insect flight flexible wings reduced-order modeling fluid-structure interaction flapping wing micro air vehicles aeroelasticity flow-induced noise and vibration

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fluid-structure interaction simulations of venous valves: A monolithic ALE method for large structural displacements

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INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2019年第2期35卷 e3156-e3156页

作者： Calandrini, Sara Aulisa, Eugenio Florida State Univ Dept Sci Comp 400 Dirac Sci Lib Tallahassee FL 32306 USA Texas Tech Univ Dept Math & Stat Lubbock TX 79409 USA

Venous valves are bicuspidal valves that ensure that blood in veins only flows back to the heart. To prevent retrograde blood flow, the two intraluminal leaflets meet in the center of the vein and occlude the vessel. In fluid-structure interaction (FSI) simulations of venous valves, the large structural displacements may lead to mesh deteriorations and entanglements, causing instabilities of the solver and, consequently, the numerical solution to diverge. In this paper, we propose an arbitrary Lagrangian-Eulerian (ALE) scheme for FSI simulations designed to solve these instabilities. A monolithic formulation for the FSI problem is considered, and due to the complexity of the operators, the exact Jacobian matrix is evaluated using automatic differentiation. The method relies on the introduction of a staggered in time velocity to improve stability, and on fictitious springs to model the contact force of the valve leaflets. Because the large structural displacements may compromise the quality of the fluid mesh as well, a smoother fluid displacement, obtained with the introduction of a scaling factor that measures the distance of a fluid element from the valve leaflet tip, guarantees that there are no mesh entanglements in the fluid domain. To further improve stability, a streamline upwind Petrov-Galerkin (SUPG) method is employed. The proposed ALE scheme is applied to a two-dimensional (2D) model of a venous valve. The presented simulations show that the proposed method deals well with the large structural displacements of the problem, allowing a reconstruction of the valve behavior in both the opening and closing phase.

关键词： ALE scheme fluid-structure interaction large structural displacements venous valves simulations

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A simulation model of Gerotor pumps considering fluid-structure interaction effects: Formulation and validation

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MECHANICAL SYSTEMS AND SIGNAL PROCESSING 2020年 140卷 106720-000页

作者： Pellegri, Matteo Manne, Venkata Harish Babu Vacca, Andrea Maha Fluid Power Res Ctr 1500 Kepner Dr Lafayette IN 47905 USA

Gerotors are compact, inexpensive and robust pumps generally used in hydraulic systems. Owing to their characteristic operation at low pressure (up to 30 bar), these units can be modelled using relatively simple tools considering only their fluid dynamics aspects. However, some commercially available Gerotors operate at higher pressures so that material deformation effects cannot be neglected under such conditions. This paper presents an omni-comprehensive simulation approach for Gerotor units that considers the fluid-structure interaction effects at the lateral lubricating gaps and related to the contacts between the rotors. The numerical tool consists of different submodels which allow the evaluation of the fluid dynamic features of the flow through the pump considering micro-motion effects of the rotors. This paper particularly details the novel aspects of the simulation approach, which is the introduction of submodels that account for fluid-structure interaction effects: the lateral lubricating gap models and the rotor contact models, both based on the solution of the Reynolds equation considering the deformation of the solid parts. For the model validation, a commercially available pump able to operate above 100 bar was tested at the authors' research center. The comparison between the simulation results and the experimental data clearly show the good accuracy of the model, in terms of volumetric flow and port pressure pulsation. In particular, the model allows predicting both the volumetric and the torque efficiency of the unit. Furthermore, the simulation results permit to interpret the reasons for instances of wear present in the unit. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Gerotors fluid-structure interaction CFD Pump modelling

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One-way coupled fluid-structure interaction of gas-liquid slug flow in a horizontal pipe: Experiments and simulations

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JOURNAL OF fluidS AND structureS 2020年 97卷 103083-103083页

作者： Mohmmed, Abdalellah O. Al-Kayiem, Hussain H. Osman, A. B. Sabir, Osama Knowledge Oasis Muscat Dept Mech Engn Middle East Coll Muscat Oman Univ Teknol Petronas Mech Engn Dept Seri Iskandar 32610 Perak Malaysia

Pipelines conveying a multiphase mixture must withstand the cyclic induced stresses that occur due to the alternating motion of gas pockets and liquid slugs. Few previous studies have considered gas-liquid slug flow and the associated fluid-structure interaction problems. In this study, experimental and numerical techniques were adopted to simulate and analyze the two-phase slug flow and the associated stresses in the pipe structure. In the numerical simulation, a one-way coupled fluid-structure framework was developed to explore the slug flow interaction with a horizontal pipe assembly under various superficial gas and liquid velocities. A modified Volume of fluid and finite element methods were utilized to model the fluid and structure domains. The file-based coupling technique was adopted to execute the coupling mechanism. By contrast, slug characteristics were measured experimentally, while Bi-axial strain gauges were used to capture time-varying strain signals. Excellent agreements between the predicted and measured stress results were achieved with a maximum error of 10.2 %. It was found that at constant superficial liquid velocity, the maximum induced stresses on the pipe wall increased with increasing the slug length and slug velocity. While for the slug frequency, the maximum principal stresses decreased with increasing the slug frequency. (c) 2020 Elsevier Ltd. All rights reserved.

关键词： fluid-structure interaction One-way coupling Slug flow-induced stresses Horizontal pipe

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Shaking table experiments on 3/10 reduced-scale CAP1400 spent fuel storage rack considering the effect of fluid-structure interaction

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NUCLEAR ENGINEERING AND DESIGN 2020年 369卷 110861-110861页

作者： Huang, Yijun Lu, Daogang Liu, Yu Zheng, Shu North China Elect Power Univ Sch Nucl Sci & Engn Beijing 102206 Peoples R China North China Elect Power Univ Beijing Key Lab Pass Safety Technol Nucl Energy Beijing 102206 Peoples R China

The seismic study of the spent fuel storage rack (SFSR) is of great significance for ensuring the safety of spent fuel. But it is a challenging topic for the complex nonlinear behaviors such as fluid-structure interaction (FSI), friction and impact. At present, owing to the lack of the understanding of these nonlinear behaviors, in engineering design process, the seismic analysis of SFSRs is usually conducted with a conservative method. To reduce the excessive margin in the seismic design of CAP1400 (a new reactor type developed by China) rack, we have performed a 1/10 scale shaking table experimental study in the previous work. As an extension of the previous study, a series of 3/10 reduced-scale seismic experiments considering the effect of FSI were carried out to study the scale effects in this paper. The experiments obtained friction coefficient between the rack and the tank (spent fuel pool model), the maximum sliding displacement of the rack and the fluid pressure distribution of the tank wall. Furthermore, the seismic responses of the rack under different experimental variables such as the number of racks, experimental scales and vertical excitation were derived. The results showed that the relative uncertainty of the sliding displacement response is very large. Moreover, the large sliding displacement differences between single-rack case and double-rack case indicated that fluid-structure interaction has a strong influence on sliding of rack. We adopted a generally used similarity criterion for seismic experiment of rack, and the experimental results showed the scaling analysis of fluid pressure satisfies the similarity relationship, however, the displacement results were influenced greatly by scale effect. These results can be the benchmarks for the seismic analysis of CAP1400 spent fuel storage rack under dynamic seismic loading.

关键词： CAP1400 spent fuel storage rack fluid-structure interaction Reduced-scale shaking table experiment

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A fluid-structure interaction model for numerical simulation of bridge flutter using sectional models with active control devices. Preliminary results

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JOURNAL OF SOUND AND VIBRATION 2020年 477卷 115338-000页

作者： Sangalli, Lucia Armiliato Braun, Alexandre Luis Univ Fed Rio Grande do Sul UFRGS Programa Posgrad Engn Civil PPGEC Escola Engn 3 AndarAv Osvaldo Aranha 99 BR-90035190 Porto Alegre RS Brazil

A fluid-structure interaction scheme for numerical simulation of actively controlled bridges subject to flutter instability is proposed in this work. In order to suppress or attenuate dynamic instabilities induced by the wind action on long-span bridges, control systems are proposed considering aerodynamic appendices and winglets attached to the deck structure, where control forces are continuously calculated using optimal control theory. The flow fundamental equations are solved here employing the explicit two-step Taylor-Galerkin method and the arbitrary Lagrangian-Eulerian (ALE) description. Eight-node hexahedral finite elements with one-point quadrature and hourglass stabilization are utilized for spatial discretization. Flow turbulence is modeled using Large Eddy Simulation (LES) and a partitioned coupling scheme is adopted for fluid-structure interactions. The structural system is analyzed considering the sectional model approach and a rigid-body formulation for large rotations. Different control techniques and winglet configurations are investigated using prismatic and bridge cross-sections, where control efficiency is evaluated in terms of displacement reduction and energy required by the control system. Preliminary results are obtained here employing approximate flowconditions to verify the control algorithm, where laminar flows and a two-dimensional LES-type approach are utilized. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Computational wind engineering Bridge aeroelasticity fluid-structure interaction Optimal control Large eddy simulation

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fluid-structure interaction and In Vitro Analysis of a Real Bileaflet Mitral Prosthetic Valve to Gain Insight Into Doppler-Silent Thrombosis

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JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME 2019年第10期141卷 1-9页

作者： Dimasi, Annalisa Piloni, Daniela Spreafico, Laura Votta, Emiliano Vismara, Riccardo Fiore, Gianfranco Beniamino Meskin, Masoud Fusini, Laura Muratori, Manuela Montorsi, Piero Pepi, Mauro Redaelli, Alberto Politecn Milan Dept Elect Informat & Bioengn Via Golgi 39 I-20133 Milan Italy Ctr Cardiol Monzino IRCCS Via Carlo Parea 4 I-20138 Milan Italy

Prosthetic valve thrombosis (PVT) is a serious complication affecting prosthetic heart valves. The transvalvular mean pressure gradient (MPG) derived by Doppler echocardiography is a crucial index to diagnose PVT but may result in false negatives mainly in case of bileaflet mechanical valves (BMVs) in mitral position. This may happen because MPG estimation relies on simplifying assumptions on the transvalvular fluid dynamics or because Doppler examination is manual and operator dependent. A deeper understanding of these issues may allow for improving PVT diagnosis and management. To this aim, we used in vitro and fluid-structure interaction (FSI) modeling to simulate the function of a real mitral BMV in different configurations: normally functioning and stenotic with symmetric and completely asymmetric leaflet opening, respectively. In each condition, the MPG was measured in vitro, computed directly from FSI simulations and derived from the corresponding velocity field through a Doppler-like postprocessing approach. Following verification versus in vitro data, MPG computational data were analyzed to test their dependency on the severity of fluid-dynamic derangements and on the measurement site. Computed MPG clearly discriminated between normally functioning and stenotic configurations. They did not depend markedly on the site of measurement, yet differences below 3 mm Hg were found between MPG values at the central and lateral orifices of the BMV. This evidence suggests a mild uncertainty of the Doppler-based evaluation of the MPG due to probe positioning, which yet may lead to false negatives when analyzing subjects with almost normal MPG.

关键词： prosthetic valve thrombosis Doppler silent thrombosis bileaflet mechanical valves computational fluid dynamics fluid-structure interaction

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A fluid-structure interaction Study on a Bionic Fish Fin With Non-Uniform Stiffness Distribution

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JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING-TRANSACTIONS OF THE ASME 2020年第5期142卷 051902页

作者： Luo, Yang Xiao, Qing Shi, Guangyu Univ Strathclyde Dept Naval Architecture Ocean & Marine Engn Glasgow G4 0LZ Lanark Scotland

In this paper, the propulsive performance of a caudal peduncle-fin swimmer mimicking a bio-inspired robotic fish model is numerically studied using a fully coupled FSI solver. The model consists of a rigid peduncle and a flexible fin which pitches in a uniform flow. The flexible fin is modeled as a thin plate assigned with non-uniformly distributed stiffness. A finite volume method based in-house Navier-Stokes solver is used to solve the fluid equations, while the fin deformation is resolved using a finite element code. The effect of the fin flexibility on the propulsive performance is investigated. The numerical results indicate that compliance has a significant influence on performance. Under the parameters studied in this paper, the medium flexible fin exhibits remarkable efficiency improvement, as well as thrust augment, while the least flexible fin shows no obvious difference from the rigid one. However, for the most flexible fin, although the thrust production decreases sharply, the efficiency reaches the maximum value. It should be noted that by non-uniformly distributing the rigidity across the caudal fin, our model is able to replicate some fin deformation patterns observed in both the live fish and the experimental robotic fish.

关键词： computational fluid dynamics fluid-structure interaction hydrodynamics

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One-way coupled three-dimensional fluid-structure interaction analysis of zigzag-channel supercritical CO2 printed circuit heat exchangers

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NUCLEAR ENGINEERING AND DESIGN 2020年 358卷 110434-110434页

作者： Bennett, Katrine Chen, Yi-tung Univ Nevada Dept Mech Engn Las Vegas NV 89154 USA

Printed circuit heat exchangers (PCHEs), with supercritical carbon dioxide (sCO(2)) as the working fluid, are being considered for use as recuperators and condensers in Brayton cycles for Next Generation Nuclear Plant (NGNP) projects as well as other power generation and heat transfer applications. A few experimental and numerical structural assessments of these PCHEs have been conducted, but all have been somewhat limited due to the difficulty measuring actual stresses in an operating PCHE and the computer resources needed to accurately conduct a fluid-structure interaction (FSI) examination using finite element analysis (FEA). This paper examines a previous pseudo two-dimensional (2D) study of a sodium-sCO(2) PCHE, linear elastic model and multilinear elastic hardening model results are included. Next, previously unperformed, three-dimensional (3D) one-way coupled FSI studies of two notional zigzag-channel, sCO(2) PCHEs are conducted. All results are evaluated against the stress intensity limits set forth by the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) Sections III and VIII. Most of the examined PCHEs meet the requirements for general use but exceed the maximum allowable stress intensities for application as nuclear components.

关键词： Printed circuit heat exchanger Supercritical CO2 fluid-structure interaction Boiler and pressure vessel code

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