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An efficient multiscale method for 2D dynamic analysis of the coupling system of fluid and heterogeneous structure

FINITE ELEMENTS IN ANALYSIS AND DESIGN 2014年 85卷 59-72页

作者： Liu, Hui Zhang, Hongwu Dalian Univ Technol Fac Vehicle Engn & Mech Dept Engn Mech State Key Lab Struct Anal Ind Equipment Dalian 116024 Peoples R China Wuhan Univ Sch Civil Engn Dept Engn Mech Wuhan 430072 Peoples R China

The two-dimensional dynamic analysis of the coupling system of fluid and heterogeneous structure is investigated by using an efficient multiscale computational method. The macroscopic equations of the coupling system are deduced. The liquid pressure-based and solid displacement-based coarse elements are employed for the numerical simulation. In addition, the piecewise oscillating boundary condition and the Lagrange polynomial boundary condition are used to construct the displacement base function of the solid coarse element and the pressure base function of the liquid coarse element, respectively. Furthermore, the generalized mode base functions are introduced into the multiscale base functions of both the fluid and structure coarse elements to capture the dynamic effect of the coarse element and improve the computational accuracy effectively. The predictor-corrector scheme is applied to solve the macroscopic transient response equation of the coupling system. Finally, several numerical examples are carried out to verify the validity and high efficiency of the proposed multiscale method by comparison with the fine-scale reference solutions. (C) 2014 Elsevier B.V. All rights reserved.

关键词： Multiscale computational method Heterogeneous structure fluid-structure interaction Dynamic analysis Pressure formulation

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Seismic Sloshing in a Horizontal Liquid Storage Tank

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STRUCTURAL ENGINEERING INTERNATIONAL 2014年第4期24卷 466-473页

作者： Malhotra, Praveen K. Nimse, Parag Meekins, Michael StrongMotions Inc Sharon MA 02067 USA Wood Grp Kenny Houston TX USA ITER Cryostat & VVPSS Sect Vessel Syst St Paul Les Durance France

A horizontal water storage tank was analyzed for seismic shaking at the ITER Tokamak Complex in France. The objectives were to (a) estimate the seismic forces in the tank;(b) calculate the sloshing response of the tank;(c) determine if baffles are needed to control sloshing;and (d) evaluate the possibility of using a single fixed support in the longitudinal direction to allow free thermal expansion of the tank. An approximate conservative analysis predicted very high sloshing waves and seismic forces in the tank. The fluid-structure interaction in the tank showed that only about 28% of the liquid moves with the tank wall and generates seismic forces in the longitudinal direction. The remaining 72% of the liquid sloshes near the free surface and does not generate significant seismic forces. The sloshing wave is not high enough in the longitudinal direction as the fundamental sloshing mode is not excited because of its very low natural frequency. Hence, baffles are not needed to control sloshing. The seismic force is low enough for a single fixed support to resist the entire seismic force in the longitudinal direction.

关键词： sloshing seismic tank liquid storage fluid-structure interaction finite element analysis

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Flapping and contact FSI computations with the fluid-solid interface-tracking/interface-capturing technique and mesh adaptivity

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COMPUTATIONAL MECHANICS 2014年第1期53卷 29-43页

作者： Wick, Thomas Univ Texas Austin Inst Computat Engn & Sci Austin TX 78712 USA Heidelberg Univ Inst Appl Math D-69120 Heidelberg Germany

The fluid-solid interface-tracking/interface-capturing technique (FSITICT) with arbitrary Lagrangian-Eulerian interface-tracking and Eulerian interface-capturing is applied to computations of fluid-structure interaction problems with flapping and contact. The two-dimensional model with contacting flaps is intended to represent a valve problem from biomechanics. The FSITICT is complemented with local mesh adaptivity, which significantly increases the performance of the interface-capturing component of the method. The test computations presented demonstrate how our approach works.

关键词： Finite elements fluid-structure interaction Monolithic formulation Arbitrary Lagrangian-Eulerian approach Fully Eulerian approach

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Numerical study on hydrodynamic effect of flexibility in a self-propelled plunging foil

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COMPUTERS & fluidS 2014年 97卷 1-20页

作者： Zhu, Xiaojue He, Guowei Zhang, Xing Chinese Acad Sci Inst Mech State Key Lab Nonlinear Mech LNM Beijing 100190 Peoples R China

The present study is a numerical investigation of the hydrodynamic effects of passive flexibility on a self-propelled plunging foil. In the model problem, the flow is two-dimensional, incompressible and laminar, while the flexible foil is treated as an inextensible filament. The leading-edge of the foil undergoes a prescribed harmonic oscillation in the vertical direction. In the horizontal direction, the foil is free to move and no constraint is imposed. The simulations are performed by using a solver which couples the immersed boundary method for the flow and the finite difference method for the structure. A systematic parametric study has been conducted to investigate the effects of flexibility on important physical quantities such as the cruising speed, swimming power and propulsive efficiency. It is found that optimal cruising speed is always achieved in foils with some passive flexibility and not the rigid ones. Another important finding is that optimum performance is always achieved at a forcing frequency much lower than the resonance point. Based on the simulation results, three dynamical states of a self-propelled foil have been identified with the increase of bending rigidity, i.e., non-periodic movement, periodic backward-movement and periodic forward-movement. For a flexible foil in forward movement, depending on the range of bending rigidity, either a deflected or a symmetric vortex street arises as the characteristic wake structure. It is found that moderate flexibility is beneficial to symmetry preservation in the wake, while excessive flexibility can trigger symmetry-breaking. The results obtained in the current work shed some light on the role of flexibility in flapping-based biolocomotion. (c) 2014 Elsevier Ltd. All rights reserved.

关键词： fluid-structure interaction Passive flexibility Self-propulsion Plunging foil Immersed boundary method Vortex street

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An analysis of a new stable partitioned algorithm for FSI problems. Part II: Incompressible flow and structural shells

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JOURNAL OF COMPUTATIONAL PHYSICS 2014年 268卷 399-416页

作者： Banks, J. W. Henshaw, W. D. Schwendeman, D. W. Lawrence Livermore Natl Lab Ctr Appl Sci Comp Livermore CA 94551 USA Rensselaer Polytech Inst Dept Math Sci Troy NY 12180 USA

Stable partitioned algorithms for fluid-structure interaction (FSI) problems are developed and analyzed in this two-part paper. Part I describes an algorithm for incompressible flow coupled with compressible elastic solids, while Part II discusses an algorithm for incompressible flow coupled with structural shells. The numerical approach described here for structural shells uses Robin (mixed) interface conditions for the pressure and velocity in the fluid which are derived directly from the governing equations. The resulting added-mass partitioned (AMP) algorithm is stable even for very light structures, requires no subiterations per time step, and is second-order accurate. The stability and accuracy of the AMP algorithm is evaluated for linearized FSI model problems. A normal mode analysis is performed to show that the new AMP algorithm is stable, even for the case of very light structures when added-mass effects are large. Exact traveling wave solutions are derived for the FSI model problems, and these solutions are used to verify the stability and accuracy of the corresponding numerical results obtained from the AMP algorithm for the cases of light, medium and heavy structures. A summary comparison of the AMP algorithm developed here and the one in Part I is provided. (C) 2014 Elsevier Inc. All rights reserved.

关键词： fluid-structure interaction Added mass instability Incompressible fluid flow structures Shells Beams

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On the influence of filling level in CFRP aircraft fuel tank subjected to high velocity impacts

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COMPOSITE structureS 2014年 107卷 570-577页

作者： Artero-Guerrero, J. A. Pernas-Sanchez, J. Lopez-Puente, J. Varas, D. Univ Carlos III Madrid Dept Continuum Mech & Struct Anal Madrid 28911 Spain

In this work, the process of impact that takes place in a partially filled tank is analyzed, performing a numerical simulation, in order to understand the response of the composite laminated structure. The commercial finite-element code LS-DYNA v.R7 has been used to simulate an Hydrodynamic RAM event created by a steel spherical projectile impacting a partially water-filled woven CFRP square tube using two different approaches (MM-ALE and SPH). The intralaminar and interlaminar damage have been taken into account implementing an user subroutine and by means of a cohesive interaction, respectively. Once the numerical model is validated using available experimental data, the effect of the filling level in the failure of the tank is analyzed in detail taking advantage of the information provided by the numerical model. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Carbon fiber Hydrodynamic RAM fluid-structure interaction Partially fluid-filled tank Impact Numerical simulation

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On fluid-shell coupling using an arbitrary Lagrangian-Eulerian fluid solver coupled to a positional Lagrangian shell solver

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APPLIED MATHEMATICAL MODELLING 2014年第14期38卷 3401-3418页

作者： Kuche Sanches, Rodolfo Andre Coda, Humberto Breves Fed Technol Univ Parana Civil Bldg Dept Pato Branco Parana Brazil Univ Sao Paulo Sch Engn Sao Carlos Dept Struct Engn Sao Carlos SP Brazil

In this work, we develop a partitioned algorithm for three-dimensional geometric non-linear fluid-structure interaction analysis using the finite element method. The fluid solver is explicit and its time integration based on characteristics, which automatically introduces stabilising terms on stream direction. The Navier-Stokes equations are written using the arbitrary Lagrangian-Eulerian (ALE) description, in order to accept moving boundaries and coupling with Lagrangian shell elements. The structure is modelled using a novel finite element method formulation for geometric non-linear shell dynamics. Such shell formulation, so-called positional formulation, is based on the minimum potential energy theorem, written regarding nodal positions and generalised unconstrained vectors, not displacements and rotations. These characteristics avoid the use of large rotation approximations. The coupling between the two different meshes is done by mapping the fluid boundary nodes local positions over the shell elements and vice versa, avoiding the need for matching fluid and shell nodes. The fluid mesh is adapted using a simple approach based on shell positions and velocities. The efficiency and robustness of the proposed approach is demonstrated by examples. (C) 2013 Elsevier Inc. All rights reserved.

关键词： fluid-structure interaction Positional finite element method Geometric non-linear analysis Shell Arbitrary Lagrangian-Eulerian (ALE) description

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Vortex-induced vibration of a bottom fixed flexible circular beam

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OCEAN ENGINEERING 2014年 88卷 463-471页

作者： Oviedo-Tolentino, F. Perez-Gutierrez, F. G. Romero-Mendez, R. Hernandez-Guerrero, A. Univ Autdnoma San Luis Potosi Fac Ingn San Luis Potosi 78290 Mexico Univ Guanajuato Dept Mech Engn Guanajuato Mexico

In this paper, we study the vortex-induced vibration of a bottom fixed circular cylinder with a 0.126 mass damping ratio and blockage ratio lower than 1%. The experiments were performed in a water tunnel at low Reynolds numbers (90 < Re < 350). The free end path of the cylinder was analyzed using a particle tracking velocimetry technique, while the shedding vortex modes were analyzed using a dye injection flow visualization technique. The results show a lock-in zone characterized by three recognizable regions which correspond to the: (1) initial, (2) upper and (3) lower branches. In the first region, the vortexshedding can occur at different cylinder frequencies for a fixed Reynolds number. It is also observed that the combined fluid-cylinder response is dominated mainly by the natural frequency of the cylinder in still water and by the vortex-shedding frequency of a stationary cylinder. In the second region, the combined responses are dominated by the natural frequencies in both still Water and still air. Finally, in the last region the vortex shedding and the cylinder frequency match very accurately with the natural frequency in still air. (c) 2014 Elsevier Ltd. All rights reserved.

关键词： Vortex-induced vibration fluid-structure interaction Lock-in region

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Stability of a flexible insert in one wall of an inviscid channel flow

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JOURNAL OF fluidS AND structureS 2014年 48卷 435-450页

作者： Burke, Meagan A. Lucey, Anthony D. Howell, Richard M. Elliott, Novak S. J. Curtin Univ Dept Mech Engn Fluid Dynam Res Grp Perth WA 6845 Australia

A hybrid of computational and theoretical methods is extended and used to investigate the instabilities of a flexible surface inserted into one wall of an otherwise rigid channel conveying an inviscid flow. The computational aspects of the modelling combine finite-difference and boundary-element methods for structural and fluid elements respectively. The resulting equations are coupled in state-space form to yield an eigenvalue problem for the fluid-structure system. In tandem, the governing equations are solved to yield an analytical solution applicable to inserts of infinite length as an approximation for modes of deformation that are very much shorter than the overall length of the insert. A comprehensive investigation of different types of inserts - elastic plate, damped flexible plate, tensioned membrane and spring-backed flexible plate - is conducted and the effect of the proximity of the upper channel wall on stability characteristics is quantified. Results show that the presence of the upper-channel wall does not significantly modify the solution morphology that characterises the corresponding open-flow configuration, i.e. in the absence of the rigid upper channel wall. However, decreasing the channel height is shown to have a very significant effect on instability-onset flow speeds and flutter frequencies, both of which are reduced. The channel height above which channel-confinement effects are negligible is shown to be of the order of the wavelength of the critical mode at instability onset. For spring-backed flexible plates the wavelength of the critical mode is much shorter than the insert length and we show very good agreement between the predictions of the analytical and the state-space solutions developed in this paper. The small discrepancies that do exist are shown to be caused by an amplitude modulation of the critical mode on an insert of finite length that is unaccounted for in the travelling-wave assumption of the analytical model. Overall, the

关键词： fluid-structure interaction Boundary-element method Finite-difference method Eigen-analysis Divergence Flutter

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Enhanced Vortex Shedding in a 183 m Industrial Chimney

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ADVANCES IN STRUCTURAL ENGINEERING 2014年第7期17卷 951-960页

作者： Belver, A. V. Koo, K. Iban, A. L. Brownjohn, J. M. W. Goddard, C. Ctr Tecnol CARTIF Valladolid 47151 Spain Univ Exeter Dept Engn Exeter Devon England Univ Valladolid Escuela Ingn Ind ITAP E-47011 Valladolid Spain Bierrum Int Ltd Barton Le Clay Beds England

This paper shows how numerical simulation can be used to explain the dynamic behaviour of two chimneys in close proximity. For similar wind speeds, the dynamic response of the leeward chimney depends on alignment of wind directions with a vector from the new to the old chimney. Evidence is presented that Enhanced Vortex Shedding (EVS) caused significant vibrations on the old 183 m high reinforced concrete chimney at Rugeley Power Station during several years of coexistence with its replacement. Strong vibrations were observed under certain conditions of wind speed and direction during construction of the new chimney, consistent with predictions of a performance study. To avoid excessive response of the old chimney during its final years of coexistence with the new one, a tuned mass damper (TMD) was installed together with a monitoring system to verify the effectiveness of the TMD. The monitoring system allowed confirming that vibration levels for winds from the south-west direction of the new chimney were higher than for similar wind speeds from other directions, a finding validated by numerical simulation using advanced computational fluid dynamics (CFD) and fluid-structure interaction (FSI) techniques.

关键词： CFD fluid-structure interaction vortex induced vibrations inline and staggered interference orbit plots

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