The Experts below are selected from a list of 150351 Experts worldwide ranked by ideXlab platform
Takeo Takahashi - One of the best experts on this subject based on the ideXlab platform.
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Approximate controllability and stabilizability of a linearized System for the Interaction between a viscoelastic fluid and a rigid body
2020Co-Authors: Debanjana Mitra, Arnab Roy, Takeo TakahashiAbstract:We study control properties of a linearized fluid-Structure Interaction System, where the Structure is a rigid body and where the fluid is a viscoelastic material. We establish the approximate controllability and the exponential stabilizability for the velocities of the fluid and of the rigid body and for the position of the rigid body. In order to prove this, we prove a general result for this kind of Systems that generalizes in particular the case without Structure. The exponential stabilization of the System is obtained with a finite-dimensional feedback control acting only on the momentum equation on a subset of the fluid domain and up to some rate that depends on the coefficients of the System. We also show that, as in the case without Structure, the System is not exactly null-controllable in finite time.
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Lp theory for the Interaction between the incompressible Navier-Stokes System and a damped plate
2020Co-Authors: Debayan Maity, Takeo TakahashiAbstract:We consider a viscous incompressible fluid governed by the Navier-Stokes System written in a domain where a part of the boundary is moving as a damped beam under the action of the fluid. We prove the existence and uniqueness of global strong solutions for the corresponding fluid-Structure Interaction System in an Lp-Lq setting. The main point in the proof consists in the study of a linear parabolic System coupling the non stationary Stokes System and a damped beam. We show that this linear System possesses the maximal regularity property by proving the R-sectoriality of the corresponding operator. The proof of the main results is then obtained by an appropriate change of variables to handle the free boundary and a fixed point argument to treat the nonlinearities of this System.
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Stabilization of a rigid body moving in a compressible viscous fluid
Journal of Evolution Equations, 2020Co-Authors: Arnab Roy, Takeo TakahashiAbstract:We consider the stabilizability of a fluid-Structure Interaction System where the fluid is viscous and compressible and the Structure is a rigid ball. The feedback control of the System acts on the ball and corresponds to a force that would be produced by a spring and a damper connecting the center of the ball to a fixed point $$h_1$$ h 1 . We prove the global-in-time existence of strong solutions for the corresponding System under a smallness condition on the initial velocities and on the distance between the initial position of the center of the ball and $$h_1$$ h 1 . Then, we show with our feedback law, that the fluid and the Structure velocities go to 0 and that the center of the ball goes to $$h_1$$ h 1 as $$t\rightarrow \infty $$ t → ∞ .
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Existence of contacts for the motion of a rigid body into a viscous incompressible fluid with the Tresca boundary conditions
2019Co-Authors: Matthieu Hillairet, Takeo TakahashiAbstract:We consider a fluid-Structure Interaction System composed by a rigid ball immersed into a viscous in-compressible fluid. The motion of the Structure satisfies the Newton laws and the fluid equations are the standard Navier-Stokes System. At the boundary of the fluid domain, we use the Tresca boundary conditions, that permit the fluid to slip tangentially on the boundary under some conditions on the stress tensor. More precisely, there is a threshold determining if the fluid can slip or not and there is a friction force acting on the part where the fluid can slip. Our main result is the existence of contact in finite time between the ball and the exterior boundary of the fluid for this System in the bidimensional case and in presence of gravity.
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Gevrey regularity for a System coupling the Navier-Stokes System with a beam : the non-flat case
2019Co-Authors: Mehdi Badra, Takeo TakahashiAbstract:We consider a bi-dimensional viscous incompressible fluid in Interaction with a beam located at its boundary. We show the existence of strong solutions for this fluid-Structure Interaction System, extending a previous result [3] where we supposed that the initial deformation of the beam was small. The main point of the proof consists in the study of the linearized System and in particular in proving that the corresponding semigroup is of Gevrey class.
Jiang Xin-liang - One of the best experts on this subject based on the ideXlab platform.
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Analysis of soil-Structure Interaction System based on mixed branch mode and constrained mode two-step method
Journal of Earthquake Engineering and Engineering Vibration, 2010Co-Authors: Wang Fei, Jiang Xin-liangAbstract:In order to introduce the effect of nonlinear soil-Structure Interaction during the Structure design process,based on the branch mode synthesis method and the mixed linear-nonlinear constrained mode synthesis method,the mixed branch mode and constrained mode method suitable for non-linear soil-Structure Interaction System is proposed.The material nonlinearity of Structure and soil could be considered effectively by using this method,and it is easier to inspect the influence of soil-Structure Interaction on superStructure.Furthermore,a mixed two-step method is also proposed on the basis of the mixed branch mode and constrained mode method and applied to the seismic analysis of soil-frame Interaction System.The results indicate that the mixed two-step method could analyze superStructure and soil separately in consideration of material nonlinearity of Structure and soil.This method is also beneficial to consider the effect of soil-Structure Interaction by only analyzing the superStructure model while using the professional design programs.It provides convenient method to consider the effect of soil-Structure Interaction during practical engineering calculation.
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PARAMETRIC RESEARCH ON SOIL-IRREGULAR Structure Interaction System CONSIDERING ASYMMETRIC FOUNDATION
Engineering mechanics, 2010Co-Authors: Jiang Xin-liangAbstract:In order to study the influence of asymmetric foundation on soil-irregular Structure System, the vibration equation considering foundation with mass eccentricity and stiffness eccentricity was established. A MATLAB program was developed based on the solution of the vibration equation decoupled by forcing decoupling method to analyze the influence of two kinds of foundation eccentricity on the Structure. It concluded that mass eccentricity of foundation has slight impact on the Structure, but the stiffness eccentricity has a large influence on the Structure, especially on the torsional response. The conclusions derived by parametric research previously are verified by time history analysis of Interaction System with foundation stiffness eccentricities of ?0.6 and 0.6.
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RANGE OF PARAMETERS AND ITS PERFORMANCE RESEARCH ON TORSIONAL COUPLING OF SOIL-ASYMMETRIC Structure Interaction System
Engineering mechanics, 2009Co-Authors: Jiang Xin-liangAbstract:In order to study the influence of foundation soil on eccentric Structure, this paper sets up the simplified foundation-asymmetric Structure Interaction model and derives the main influencing factors and their ranges that influence the Structure's elastic response by solving the lateral-torsional coupling equation of the foundation-asymmetric Structure Interaction System. The parameters' elastic influencing rules derived by time-history analysis coincide well with analytic solutions, which verify the effectiveness of the time-history analysis. Through using the time-history analysis, this paper studies the laws how the parameters influence the inelastic seismic response. It produces local amplification of relative displacement by comparing the inelastic seismic response with the elastic seismic response. The conclusions provide references for the design and calculation of asymmetric Structures under earthquake.
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Research on superharmonic resonance and subharmonic resonance of nonlinear soil Structure Interaction System considering spatial effect
World Earthquake Engineering, 2006Co-Authors: Jiang Xin-liangAbstract:In this paper,one massless foundation-soil-Structure Interaction model considering spatial effect is established,and the model is simplified as a three-freedom System,then the nonlinear coupling equation of horizontal motion and torsion motion for the simplified System is gained.The superharmonic resonance and subharmonic resonance behavior of the soil-Structure Interaction System is studied using perturbation method.Some conclusions which are different from linear Systems have been drawn through the analyses of numerical example.More profound theoretical basis is provided for seismic analysis of nonlinear Structures.
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Research on superharmonic resonance and subharmonic resonance of soil-nonlinear Structure Interaction System
Earthquake Engineering and Engineering Vibration, 2001Co-Authors: Jiang Xin-liangAbstract:In this paper, Duffing oscillator's model is taken as a restoring force of the superStructure, and a lumped parameter model is used to simulate the viscoelastic halfspace. The perturbation analysis is used to study the conditions which give rise to the superharmonic resonance and subharmonic resonance. Then the nonlinear dynamical behavior is analyzed when the superharmonic resonance or the subharmonic resonance occurs. Some conclusions are drawn through the analysis of numerical examples.
Hemanshu R. Pota - One of the best experts on this subject based on the ideXlab platform.
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The optimal placement of actuator and sensor for active noise control of sound–Structure Interaction Systems
Smart Materials and Structures, 2008Co-Authors: Suwit Pulthasthan, Hemanshu R. PotaAbstract:This paper presents new objective functions and a practical method for finding the optimal placement of actuator and sensor for a sound?Structure Interaction System. The developed method for optimal actuator and sensor positioning is based on an energy-based approach and model uncertainty. The optimal actuator and sensor location obtained is used to construct a feedback controller using a minimax LQG control design method for reducing acoustic potential energy caused by Structure-borne sound inside the acoustic cavity. The experimental demonstration of the novel method presented in this paper attenuates structural vibration up to 17?dB over the entire frequency range of interest and the associated noise up to 10?dB without explicit knowledge of the acoustic model.
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Acoustic noise reduction in sound-Structure Interaction System
2004 43rd IEEE Conference on Decision and Control (CDC) (IEEE Cat. No.04CH37601), 2004Co-Authors: Hemanshu R. Pota, Suwit Pulthasthan, Ian R. PetersenAbstract:This paper presents the experimental results in the application of feedback control of acoustic noise in an cavity of timber with a flexible lid of an aluminium sheet. The cavity is considered as a sound-Structure Interaction System. The paper demonstrates a practical way to design a controller using minimax LQG methods. It is also shown that the proper choice of a weighting function is an important step in the controller design. The designed controller with low-order is not only robust to unmodeled dynamics and parametric uncertainties but also convenient to being output feedback with guaranteed stability. In addition, the interesting results can be further improved by proper selection of actuator and sensor placement.
Clarence W Rowley - One of the best experts on this subject based on the ideXlab platform.
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connections between resonance and nonlinearity in swimming performance of a flexible heaving plate
Journal of Fluid Mechanics, 2020Co-Authors: Andres Goza, Daniel Floryan, Clarence W RowleyAbstract:We investigate the role of resonance in finite-amplitude swimming of a flexible flat plate in a viscous fluid. The role of resonance in performance remains unclear for two reasons: (i) a lack of definition of resonance for the fully coupled fluid–Structure Interaction System in a viscous flow, and (ii) the presence of nonlinear effects, which makes it difficult to disentangle resonant and non-resonant mechanisms in finite-amplitude swimming. We address point (i) and provide an unambiguous definition for System resonance by computing global linear stability modes of the fully coupled fluid–Structure Interaction System that account for the viscous fluid, the plate and the coupling between them. We resolve point (ii) by considering high-fidelity nonlinear simulations of Systematically increased amplitude. By comparing the results for different amplitudes with one another and with the linear stability modes, we separate linear and/or resonant effects from nonlinear and/or non-resonant effects. Resonant behaviour is observed over a wide range of plate stiffnesses, with peaks in trailing-edge motion and thrust occurring near the resonant frequency defined by the global linear analysis. The peaks broaden and weaken with increasing heave amplitude, consistent with an increased damping effect from the fluid. At the same time, non-resonant mechanisms are present at large heave amplitudes. The input power exhibits qualitatively different dynamics at large heave amplitudes compared to smaller heave amplitudes, where resonance dominates. Moreover, leading-edge separation is present for stiff plates at large heave amplitudes, which can drastically alter the performance characteristics from what one would expect through linear predictions.
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connections between resonance and nonlinearity in swimming performance of a flexible heaving plate
arXiv: Fluid Dynamics, 2019Co-Authors: Andres Goza, Daniel Floryan, Clarence W RowleyAbstract:We investigate the role of resonance in finite-amplitude swimming of a flexible flat plate in a viscous fluid. The role of resonance in performance remains unclear for two reasons: i) a lack of definition of resonance for the fully-coupled fluid-Structure Interaction System in a viscous flow, and ii) the presence of nonlinear effects, which makes it difficult to disentangle resonant and non-resonant mechanisms in finite-amplitude swimming. We address point i) and provide an unambiguous definition for System resonance by computing global linear stability modes of the fully-coupled fluid-Structure Interaction System that account for the viscous fluid, the plate, and the coupling between them. We then resolve point ii) by considering high-fidelity nonlinear simulations of Systematically increased amplitude. By comparing the results for different amplitudes with one another and with the linear stability modes, we separate linear and/or resonant effects from nonlinear and/or non-resonant effects. Resonant behavior is observed over a wide range of plate stiffnesses, with peaks in trailing-edge motion and thrust occurring near the resonant frequency defined by the global linear analysis. The peaks broaden and weaken with increasing heave amplitude, consistent with an increased damping effect from the fluid. At the same time, non-resonant mechanisms are present at large heave amplitudes. The input power exhibits qualitatively different dynamics at large heave amplitudes compared to smaller heave amplitudes, where resonance dominates. Moreover, leading-edge separation is present for stiff plates at large heave amplitudes, which can drastically alter the performance characteristics from what one would expect through linear predictions.
Alessandro Valiani - One of the best experts on this subject based on the ideXlab platform.
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modeling blood flow in viscoelastic vessels the 1d augmented fluid Structure Interaction System
Computer Methods in Applied Mechanics and Engineering, 2020Co-Authors: Giulia Bertaglia, Valerio Caleffi, Alessandro ValianiAbstract:Abstract Nowadays mathematical models and numerical simulations are widely used in the field of hemodynamics, representing a valuable resource to better understand physiological and pathological processes in different medical sectors. The theory behind blood flow modeling is closely related to the study of incompressible flow through compliant thin-walled tubes, starting from the incompressible Navier–Stokes equations. Furthermore, the mechanical Interaction between blood flow and vessels wall must be properly described by the model. Recent works showed the benefits of characterizing the rheology of the vessel wall through a viscoelastic law. Taking into account the viscous contribution of the wall material and not simply the elastic one leads to a more realistic representation of the vessel behavior, which manifests not only an instantaneous elastic strain but also a viscous damping effect on pulse pressure waves, coupled to energy losses. In this context, the aim of this work is to propose an easily extensible one-dimensional mathematical model able to accurately capture fluid–Structure Interactions. The originality of the model lies in the introduction of a viscoelastic tube law in PDE form, valid for both arterial and venous networks, leading to an augmented fluid–Structure Interaction System. In contrast to well established mathematical models, the proposed one is natively hyperbolic. The model is solved with an efficient and robust second-order numerical scheme; the time integration is based on an Implicit–Explicit Runge–Kutta scheme conceived for applications to hyperbolic Systems with stiff relaxation terms. The validation of the proposed model is performed on several different test cases. Results obtained in Riemann problems, adopting a simple elastic tube law for the characterization of the vessel wall, are compared with available exact solutions. To validate the contribution given by the viscoelastic term, the Method of Manufactured Solutions has been applied. Specific tests have been designed to verify the well-balancing with respect to fluid-at-rest condition and the accuracy-preserving property of the scheme. Finally, a specific test case with an inlet pulse pressure wave has been designed to assess the effects of viscoelasticity with respect to a simple elastic behavior of the vessel wall. The complete code, written in MATLAB (MathWorks Inc.) language, with the implemented test cases, is made available in Mendeley Data repository.
