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VIBRO-ACOUSTIC ANALYSIS OF LAMINATED DOUBLE GLAZING USING THE FORCE IDENTIFICATION METHOD

JOURNAL OF THEORETICAL AND APPLIED MECHANICS 2014年第4期52卷 895-904页

作者： Ben Jdidia, Mounir Akrout, Ali Tounsi, Dhouha Fakhfakh, Tahar Haddar, Mohamed Natl Sch Engn Sfax Dept Mech Engn Mech Modelling & Prod Res Lab Sfax Tunisia

This paper presents a procedure for identifying wave forms and excitation frequencies of some forces applied on a given complex fluid-structure coupled system by using only its vibro-acoustic response. The considered concept is called the Independent Component Analysis (ICA) which is based on the Blind Source Separation (BSS). In this work, the ICA method is exploited in order to determine the excitation force applied to a thin-film laminated double glazing system enclosing a thin fluid cavity and limited by an elastic joint. The dynamic response of the studied fluid-structure coupled system is determined by finite element discretization and minimization of the homogenized energy functional of the coupled problem. This response will serve as the input for the ICA algorithm in order to extract the applied excitation.

关键词： fluid-structure interaction thin-film laminated plate ICA excitation force Kurtosis

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Shock response of a two-fluid cylindrical shell system containing a rigid core

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COMPUTERS & fluidS 2014年 96卷 215-225页

作者： Iakovlev, S. Mitchell, M. Lefieux, A. Murray, R. Dalhousie Univ Dept Engn Math & Internetworking Halifax NS B3J 2X4 Canada Inst Univ Super Pavia I-27100 Pavia Italy Dalhousie Univ Dept Mech Engn Halifax NS B3J 2X4 Canada

A submerged fluid-filled cylindrical shell containing a rigid co-axial core and subjected to an external shock wave is considered, and the fluid dynamics of such interaction is analyzed for the most general scenario of two different fluids. It is demonstrated that the phenomenology of the interaction in this case is fundamentally different from the case when the fluids are identical. In the latter case, all the most important wave propagation, reflection and focusing phenomena in the internal fluid that are observed for the shell without a core are also present when a core is placed inside the fluid, unless the core directly occupies the region of the fluid where the phenomena occur. When the fluids are different, however, it is possible that some phenomena are not observed even when the core does not occupy the respective region of the fluid. Due to the very high pressure that is often associated with the phenomena in question, this observation is of considerable practical significance in that it suggests the possibility of a very significant reduction of the peak pressure in the system by means of placing an additional structure inside the primary shell. The observations made are quantified using a number of pressure time-histories aimed at facilitating the pre-design analysis of shock-subjected fluid-interacting structures. (c) 2014 Elsevier Ltd. All rights reserved.

关键词： fluid-structure interaction Shock response

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Shape Recovery of Elastic Capsules from Shear Flow Induced Deformation

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Communications in Computational Physics 2014年第6期16卷 56-74页

作者： John Gounley Yan Peng Department of Mathematics and Statistics Old Dominion UniversityNorfolkVA 23529USA.

Red blood cells undergo substantial shape changes in *** as a viscoelastic capsule,their deformation and equilibrium behavior has been extensively *** consider how 2D capsules recover their shape,after having been deformed to’equilibrium’behavior by shear *** fluid-structure interaction is modeled using the multiple-relaxation time lattice Boltzmann(LBM)and immersed boundary(IBM)*** the capsule’s shape recovery with the Taylor deformation parameter,we find that a single exponential decay model suffices to describe the recovery of a circular ***,for biconcave capsules whose equilibrium behaviors are tank-treading and tumbling,we posit a two-part recovery,modeled with a pair of exponential decay *** consider how these two recovery modes depend on the capsule’s shear elasticity,membrane viscosity,and bending stiffness,along with the ratio of the viscosity of the fluid inside the capsule to the ambient fluid *** find that the initial recovery mode for a tank-treading biconcave capsule is dominated by shear elasticity and membrane *** the other hand,the latter recovery mode for both tumbling and tank-treading capsules,depends clearly on shear elasticity,bending stiffness,and the viscosity ratio.

关键词： fluid-structure interaction shape recovery lattice Boltzmann method immersed boundary method.

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Modeling, shape analysis and computation of the equilibrium pore shape near a PEM-PEM intersection

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JOURNAL OF MATHEMATICAL ANALYSIS AND APPLICATIONS 2014年第1期410卷 241-256页

作者： Berg, Peter Kimmerle, Sven-Joachim Novruzi, Arian Univ Bundeswehr Munchen Munich Germany Univ Ottawa Ottawa ON K1N 6N5 Canada

In this paper we study the equilibrium shape of an interface that represents the lateral boundary of a pore channel embedded in an elastomer. The model consists of a system of PDEs, comprising a linear elasticity equation for displacements within the elastomer and a nonlinear Poisson equation for the electric potential within the channel (filled with protons and water). To determine the equilibrium interface, a variational approach is employed. We analyze: (i) the existence and uniqueness of the electrical potential, (ii) the shape derivatives of state variables and (iii) the shape differentiability of the corresponding energy and the corresponding Euler-Lagrange equation. The latter leads to a modified Young-Laplace equation on the interface. This modified equation is compared with the classical Young-Laplace equation by computing several equilibrium shapes, using a fixed point algorithm. (C) 2013 Elsevier Inc. All rights reserved.

关键词： Equilibrium shape Shape calculus fluid-structure interaction Free boundary Variational gradient method Young-Laplace law PEM fuel cell

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MODAL CHARACTERISTIC ANALYSIS OF THE APR1400 NUCLEAR REACTOR INTERNALS FOR SEISMIC ANALYSIS

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NUCLEAR ENGINEERING AND TECHNOLOGY 2014年第5期46卷 689-698页

作者： Park, Jong-Beom Choi, Youngin Lee, Sang-Jeong Park, No-Cheol Park, Kyoung-Su Park, Young-Pil Park, Chan-Il Yonsei Univ Dept Mech Engn Seoul 120749 South Korea Gachon Univ Dept Mech Engn Songnam 461701 Gyeonggi Do South Korea Korea Inst Nucl Safety Taejon 305338 South Korea

Reactor internals are sensitive to dynamic loads such as earthquakes and flow induced vibration. Thus, it is essential to identify the dynamic characteristics to evaluate the seismic integrity of the structures. However, a full-sized system is too large to perforni modal experiments, making it difficult to extract data on its modal characteristics. In this research, we constructed a finite element model of the APR1400 reactor internals to identify their modal characteristics. The commercial reactor was selected to reflect the actual boundary conditions. Our FE model was constructed based on scale-similarity analysis and fluid-structure interaction investigations using a fabricated scaled-down model.

关键词： Reactor Internals Scaled-down Model fluid-structure interaction Finite Element Method Commercial Reactor

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Alteration of Residual Circulation Due to Large-Scale Infrastructure in a Coastal Plain Estuary

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ESTUARIES AND COASTS 2014年第2期37卷 493-507页

作者： Meyers, Steven D. Linville, Amanda J. Luther, Mark E. Univ S Florida Coll Marine Sci St Petersburg FL 33701 USA

Large-scale human-built infrastructure is shown to alter the salinity and subtidal residual flow in a realistic numerical simulation of hydrodynamic circulation in a coastal plain estuary (Tampa Bay). Two model scenarios are considered. The first uses a modern bathymetry and boundary conditions from the years 2001-2003. The second is identical to the first except that the bathymetry is based on depth soundings from the pre-construction year 1879. Differences between the models' output can only result from changes in bay morphology, in particular built infrastructure such as bridges, causeways, and dredging of the shipping channel. Thirty-day means of model output are calculated to remove the dominant tidal signals and allow examination of the subtidal dynamics. Infrastructure is found to steepen the mean axial salinity gradient by similar to 40% when there is low freshwater input but flatten by similar to 25% under more typical conditions during moderate freshwater inflow to the estuary. Deepening of the shipping channel also increases the magnitude of the residual Eulerian circulation, allowing for larger up-estuary salt transport. Local bathymetry and morphology are important. Some regions within the estuary show little change in residual circulation due to infrastructure. In others, the residual circulation can vary by a factor of 4 or more. Major features of the circulation and changes due to infrastructure can be partially accounted for with linear theory.

关键词： Estuary Residual circulation Bathymetry fluid-structure interaction Infrastructure Exchange flow

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On well-posedness and small data global existence for an interface damped free boundary fluid-structure model

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NONLINEARITY 2014年第3期27卷 467-499页

作者： Ignatova, Mihaela Kukavica, Igor Lasiecka, Irena Tuffaha, Amjad Stanford Univ Dept Math Stanford CA 94305 USA Univ So Calif Dept Math Los Angeles CA 90089 USA Univ Memphis Dept Math Sci Memphis TN 38152 USA Polish Acad Sci IBS Warsaw Poland Petr Inst Dept Math Abu Dhabi U Arab Emirates

We address a fluid-structure system which consists of the incompressible Navier-Stokes equations and a damped linear wave equation defined on two dynamic domains. The equations are coupled through transmission boundary conditions and additional boundary stabilization effects imposed on the free moving interface separating the two domains. Given sufficiently small initial data, we prove the global-in-time existence of solutions by establishing a key energy inequality which in addition provides exponential decay of solutions.

关键词： Navier-Stokes equations fluid-structure interaction long time behaviour global solutions damped wave equation

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Numerical Study of Stability and Accuracy of the Immersed Boundary Method Coupled to the Lattice Boltzmann BGK Model

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Communications in Computational Physics 2014年第6期16卷 136-168页

作者： Yongguang Cheng Luoding Zhu Chunze Zhang State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan UniversityWuhan 430072P.R.China. Department of Mathematical Sciences Indiana University-Purdue University IndianapolisIndianapolisIN 46202USA.

This paper aims to study the numerical features of a coupling scheme between the immersed boundary(IB)method and the lattice Boltzmann BGK(LBGK)model by four typical test problems:the relaxation of a circular membrane,the shearing flow induced by a moving fiber in the middle of a channel,the shearing flow near a non-slip rigid wall,and the circular Couette flow between two inversely rotating *** accuracy and robustness of the IB-LBGK coupling scheme,the performances of different discrete Dirac delta functions,the effect of iteration on the coupling scheme,the importance of the external forcing term treatment,the sensitivity of the coupling scheme to flow and boundary parameters,the velocity slip near non-slip rigid wall,and the origination of numerical instabilities are investigated in detail via the four test *** is found that the iteration in the coupling cycle can effectively improve stability,the introduction of a second-order forcing term in LBGK model is crucial,the discrete fiber segment length and the orientation of the fiber boundary obviously affect accuracy and stability,and the emergence of both temporal and spatial fluctuations of boundary parameters seems to be the indication of numerical *** elaborate results shed light on the nature of the coupling scheme and may benefit those who wish to use or improve the method.

关键词： Immersed boundary method lattice Boltzmann method fluid-structure interaction flexible boundary complex boundary accuracy stability verification

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Projection Preconditioner for Solving the Implicit Immersed Boundary Equations

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Numerical Mathematics(Theory,Methods and Applications) 2014年第4期7卷 473-498页

作者： Qinghai Zhang Robert D.Guy Bobby Philip Department of Mathematics University of UtahSalt Lake CityUT 84112USA Department ofMathematics University of California DavisDavisCA 95616USA Oak Ridge National Laboratory Oak RidgeTN 37831USA

This paper presents a method for solving the linear semi-implicit immersed boundary equations which avoids the severe time step restriction presented by explicit-time *** Lagrangian variables are eliminated via a Schur complement to form a purely Eulerian saddle point system,which is preconditioned by a projection operator and then solved by a Krylov subspace *** the viewpoint of projection methods,we derive an ideal preconditioner for the saddle point problem and compare the efficiency of a number of simpler preconditioners that approximate this perfect *** low Reynolds number and high stiffness,one particular projection preconditioner yields an efficiency improvement of the explicit IB method by a factor around *** speed-ups over explicit-time method are achieved for Reynolds number below *** speedup increases as the Eulerian grid size and/or the Reynolds number are further reduced.

关键词： fluid-structure interaction immersed boundary method projection method preconditioning

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A noninvasive approach to determine viscoelastic properties of an individual adherent cell under fluid flow

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JOURNAL OF BIOMECHANICS 2014年第6期47卷 1537-1541页

作者： Qiu, Jun Baik, Andrew D. Lu, X. Lucas Hillman, Elizabeth M. C. Zhuang, Zhuo Dong, Cheng Guo, X. Edward Tsinghua Univ Sch Aerosp Beijing 100084 Peoples R China Columbia Univ Bone Bioengn Lab New York NY 10027 USA Columbia Univ Dept Biomed Engn Lab Funct Opt Imaging New York NY 10027 USA Univ Delaware Dept Mech Engn Newark DE 19716 USA Penn State Univ Dept Bioengn University Pk PA 16802 USA

Mechanical properties of cells play an important role in their interaction with the extracellular matrix as well as the mechanotransduction process. Several in vitro techniques have been developed to determine the mechanical properties of cells, but none of them can measure the viscoelastic properties of an individual adherent cell in fluid flow non-invasively. In this study, techniques of fluid-structure interaction (FSI) finite element method and quasi-3-dimensional (quasi-3D) cell microscopy were innovatively applied to the frequently used flow chamber experiment, where an adherent cell was subjected to fluid flow. A new non-invasive approach, with cells at close to physiological conditions, was established to determine the viscoelastic properties of individual cells. The results showed an instantaneous modulus of osteocytes of 0.49 +/- 0.11 kPa, an equilibrium modulus of 0.31 +/- 0.044 kPa, and an apparent viscosity coefficient of 4.07 +/- 1.23 kPa s. This new quantitative approach not only provides an excellent means to measure cell mechanical properties, but also may help to elucidate the mechanotransduction mechanisms for a variety of cells under fluid flow stimulation. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Cell mechanical property Viscoelastic fluid-structure interaction Finite element method Osteocyte

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