We investigate optimization problems in which the state is given in terms of fluid-structure interactions. The coupled problem is formulated with the help of the ALE (arbitrary Lagrangian-Eulerian) mapping. The soluti...
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We investigate optimization problems in which the state is given in terms of fluid-structure interactions. The coupled problem is formulated with the help of the ALE (arbitrary Lagrangian-Eulerian) mapping. The solution approach is based on derivative-based optimization algorithms in which the derivatives are obtained with the help of the Lagrange formalism, leading to the so-called optimality system. The optimality system is then solved with Newton's method. The focus is on the proper derivation of the adjoint equations guiding the optimization formalism. Moreover, special attention is given to the adjoint information transport between the fluid and structure subproblems. Numerical tests are used to substantiate the theoretical framework.
We analyze a splitting method for a canonical fluidstructureinteraction problem. The splitting method uses a Robin-Robin boundary condition to define an explicit coupling between the fluid and the structure. We prov...
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We analyze a splitting method for a canonical fluidstructureinteraction problem. The splitting method uses a Robin-Robin boundary condition to define an explicit coupling between the fluid and the structure. We prove the method is stable and, furthermore, we provide an error estimate that shows the error at the final time T is O(T Delta t) where Delta t is the time step.
In this paper, we develop a novel phase-field model for fluid-structure interaction (FSI), that is capable to handle very large deformations as well as topology changes like contact of the solid to a wall. The model i...
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In this paper, we develop a novel phase-field model for fluid-structure interaction (FSI), that is capable to handle very large deformations as well as topology changes like contact of the solid to a wall. The model is based on a fully Eulerian description of the velocity field in both, the fluid and the elastic domain. Viscous and elastic stresses in the Navier-Stokes equations are restricted to the corresponding domains by multiplication with their characteristic functions. The solid is described as a hyperelastic neo-Hookean material and the elastic stress is obtained by solving an additional Oldroyd-B - like equation. Thermodynamically consistent forces are derived by energy variation. The convergence of the derived equations to the traditional sharp interface formulation of fluid-structure interaction is shown by matched asymptotic analysis. The model is evaluated in a challenging benchmark scenario of an elastic body traversing a fluid channel. A comparison to reference values from Arbitrary Lagrangian Eulerian (ALE) simulations shows very good agreement. We highlight some distinct advantages of the new model, like the avoidance of re-triangulations and the stable inclusion of surface tension. Further, we demonstrate how simple it is to include contact dynamics into the model, by simulating a ball bouncing off a wall. We extend this scenario to include adhesion of the ball, which to our knowledge, cannot be simulated with any other FSI model. While we have restricted simulations to fluid-structure interaction, the model is capable to simulate any combination of viscous fluids, visco-elastic fluids and elastic solids. (C) 2018 Elsevier Inc. All rights reserved.
This paper is concerned with the fully coupled ('monolithic') solution of large-displacement fluid-structure interaction problems by Newton's method. We show that block-triangular approximations of the Jac...
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This paper is concerned with the fully coupled ('monolithic') solution of large-displacement fluid-structure interaction problems by Newton's method. We show that block-triangular approximations of the Jacobian matrix, obtained by neglecting selected fluid-structure interaction blocks, provide good preconditioners for the solution of the linear systems with GMRES. We present an efficient approximate implementation of the preconditioners, based on a Schur complement approximation for the Navier-Stokes block and the use of multigrid approximations for the solution of the computationally most expensive operations. The performance of the the preconditioners is examined in representative steady and unsteady simulations which show that the GMRES iteration counts only display a mild dependence on the Reynolds number and the mesh size. The final part of the paper demonstrates the importance of consistent stabilisation for the accurate simulation of fluid-structure interaction problems. (C) 2003 Elsevier B.V. All rights reserved.
The dual-primal finite element tearing and interconnecting method (FETI-DP) is extended to systems of linear equations arising from a finite element discretization for a class of fluidstructureinteraction problems in...
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The dual-primal finite element tearing and interconnecting method (FETI-DP) is extended to systems of linear equations arising from a finite element discretization for a class of fluidstructureinteraction problems in the frequency domain. A preconditioned generalized minimal residual method is used to solve the linear equations for the Lagrange multipliers introduced on the subdomain boundaries to enforce continuity of the solution. The coupling between the fluid and the structure on the fluidstructure interface requires an appropriate choice of coarse level degrees of freedom in the FETI-DP algorithm to achieve fast convergence. Several choices are proposed and tested by numerical experiments on three-dimensional fluidstructureinteraction problems in the mid-frequency regime that demonstrate the greatly improved performance of the proposed algorithm over the standard FETI-DP method. Copyright (c) 2011 John Wiley & Sons, Ltd.
The performances of aerostatic spindle are highly affected by the fluid-structure interaction (FSI) between air film and solid structure. This paper proposes a novel modeling method to investigate the FSI of aerostati...
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The performances of aerostatic spindle are highly affected by the fluid-structure interaction (FSI) between air film and solid structure. This paper proposes a novel modeling method to investigate the FSI of aerostatic spindle system, by which the structure deformation included by air film force can be acquired. Furthermore, a virtual weight loading method is proposed to estimate the stiffness of spindle with consideration of structure deformation and gravitational eccentricity. The reliability of the proposed method is verified by experiments. Based on the proposed FSI model, the influences of air film geometrical parameters and structure dimension on the performance of aerostatic spindle are further investigated and discussed to guide the design of air spindle.
fluid-structure interaction (FSI) numerical models are now widely used in predicting blood flow transients. This is because of the importance of the interaction between the flowing blood and the deforming arterial wal...
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fluid-structure interaction (FSI) numerical models are now widely used in predicting blood flow transients. This is because of the importance of the interaction between the flowing blood and the deforming arterial wall to blood flow behaviour. Unfortunately, most of these FSI models lack rigorous validation and, thus, cannot guarantee the accuracy of their predictions. This paper presents the comprehensive validation of a two-way coupled FSI numerical model, developed to predict flow transients in compliant conduits such as arteries. The model is validated using analytical solutions and experiments conducted on polyurethane mock artery. Flow parameters such as pressure and axial stress (and precursor) wave speeds, wall deformations and oscillating frequency, fluid velocity and Poisson coupling effects, were used as the basis of this validation. Results show very good comparison between numerical predictions, analytical solutions and experimental data. The agreement between the three approaches is generally over 95%. The model also shows accurate prediction of Poisson coupling effects in unsteady flows through flexible pipes, which up to this stage have only being predicted analytically. Therefore, this numerical model can accurately predict flow transients in compliant vessels such as arteries. (c) 2009 Elsevier Ltd. All rights reserved.
Cable subsystems characterized by long, slender, and flexible structural elements are featured in numerous engineering systems. In each of them, interaction between an individual cable and the surrounding fluid is ine...
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Cable subsystems characterized by long, slender, and flexible structural elements are featured in numerous engineering systems. In each of them, interaction between an individual cable and the surrounding fluid is inevitable. Such a fluid-structure interaction has received little attention in the literature, possibly due to the inherent complexity associated with fluid and structural semidiscretizations of disparate spatial dimensions. This article proposes an embedded boundary approach for filling this gap, where the dynamics of the cable are captured by a standard finite element representation of its centerline, while its geometry is represented by a discrete surface n-ary sumation (h) that is embedded in the fluid mesh. The proposed approach is built on master-slave kinematics between and n-ary sumation (h), a simple algorithm for computing the motion/deformation of n-ary sumation (h) based on the dynamic state of , and an energy-conserving method for transferring to the loads computed on n-ary sumation (h). Its effectiveness is demonstrated for two highly nonlinear applications featuring large deformations and/or motions of a cable subsystem and turbulent flows: an aerial refueling model problem, and a challenging supersonic parachute inflation problem. The proposed approach is verified using numerical data and validated using real flight data.
fluid-structure interactions (FSI) play a crucial role in many engineering fields. However, the computational cost associated with high-fidelity aeroelastic models currently precludes their direct use in industry, esp...
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fluid-structure interactions (FSI) play a crucial role in many engineering fields. However, the computational cost associated with high-fidelity aeroelastic models currently precludes their direct use in industry, especially for strong interactions. The strongly coupled segregated problem-that results from domain partitioning-can be interpreted as an optimization problem of a fluid-structure interface residual. Multi-fidelity optimization techniques can therefore directly be applied to this problem in order to obtain the solution efficiently. In previous work, it is already shown that aggressive space mapping (ASM) can be used in this context. In this contribution, we extend the research towards the use of space mapping for FSI simulations. We investigate the performance of two other approaches, generalized space mapping and output space mapping, by application to both compressible and incompressible 2D problems. Moreover, an analysis of the influence of the applied low-fidelity model on the achievable speedup is presented. The results indicate that output space mapping is a viable alternative to ASM when applied in the context of solver coupling for partitioned FSI, showing similar performance as ASM and resulting in reductions in computational cost up to 50% with respect to the reference quasi-Newton method. Copyright (C) 2015 John Wiley & Sons, Ltd.
fluid-structure interaction (FSI) is a phenomenon caused by mutual interference between structures and the surrounding flow. Controlling FSI is important because FSI causes undesired vibration and it often affects the...
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fluid-structure interaction (FSI) is a phenomenon caused by mutual interference between structures and the surrounding flow. Controlling FSI is important because FSI causes undesired vibration and it often affects the safety and lifetime of structures. Piezoelectric materials have excellent electromechanical properties to suppress vibration. As such, piezoelectric sensors and actuators are often used for reducing not only mechanical vibration but also FSI induced vibration. A number of studies have examined active control of FSI using piezoelectric materials. In the study of the control of FSI, numerical simulations are effective because they are proper for parametric studies and reduce the need for experiments. Although a number of numerical studies examined the control of FSI using piezoelectric materials, in these studies, detailed fluid analyses were not performed and the fluid force was modeled as a simple function. As such, the existing method cannot treat complicated FSI problems. Therefore, we herein propose a general-purpose system that conducts detailed electrostatic, structural, and fluid analyses and considers an active control algorithm. We design a structure-fluid-electrostatic interaction analysis system considering active control by inserting electrostatic analysis into FSI analysis solved by the partitioned iterative method and integrating the active control algorithm. In the present study, we verify the proposed system in three ways. First, while varying the material properties of the fluid, we analyze the motion of a bimorph piezoelectric actuator in a non-flowing fluid and compare the results with those of a previous study that did not take the fluid into consideration. Second, we reproduce vortex-induced vibration (VIV), which is an FSI phenomenon using the proposed system. Third, we confirm that the active control algorithm is implemented correctly by solving the suppression of VIV with the velocity feedback control. Based on these verification
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