This paper presents a new fixed grid fluid-structure interaction scheme that can be applied to the interaction of most general structures with incompressible flow. It is based on an eXtended Finite Element Method (XFE...
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This paper presents a new fixed grid fluid-structure interaction scheme that can be applied to the interaction of most general structures with incompressible flow. It is based on an eXtended Finite Element Method (XFEM) based strategy. The extended Eulerian fluid field and the Lagrangian structural field are partitioned and iteratively coupled using Lagrange multiplier techniques for non-matching grids. The approach allows the simulation of the interaction of thin and bulky structures exhibiting large deformations. Finally, qualitative examples and a benchmark computation demonstrate key features and accuracy of the method. (C) 2007 Elsevier B.V. All rights reserved.
Partitioned Newton type solution strategies for the strongly coupled system of equations arising in the computational modelling of fluid-solid interaction require the evaluation of various coupling terms. An essential...
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Partitioned Newton type solution strategies for the strongly coupled system of equations arising in the computational modelling of fluid-solid interaction require the evaluation of various coupling terms. An essential part of all ALE type solution strategies is the fluid mesh motion. In this paper, we investigate the effect of the terms which couple the fluid flow with the fluid mesh motion on the convergence behaviour of the overall solution procedure. We show that the computational efficiency of the simulation of many fluid-solid interaction processes, including fluid flow through flexible pipes, can be increased significantly if some of these coupling terms are calculated exactly.
We present a new approach to numerical modelling of incompressible flow of fluid about an elastically mounted rigid structure with large body motions. The solution is based on the Finite Volume Particle Method (FVPM),...
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We present a new approach to numerical modelling of incompressible flow of fluid about an elastically mounted rigid structure with large body motions. The solution is based on the Finite Volume Particle Method (FVPM), a meshless generalisation of the mesh-based finite volume method. The finite volume particles are allowed to overlap, without explicit connectivity, and can therefore move arbitrarily to follow the motion of a wall. Here, FVPM is employed with a pressure projection method for fully incompressible flow coupled with motion of a rigid body. The developed extension is validated for Vortex-Induced Vibration (VIV) of a circular cylinder in laminar crossflow. To minimise computational effort, non-uniform particle size and arbitrary Lagrangian-Eulerian particle motion schemes are employed, with radial basis functions used to define the particle motion near the cylinder. Close agreement is demonstrated between the FVPM results and a reference numerical solution. Results confirm the feasibility of FVPM as a new approach to the modelling of flow with strongly coupled rigid-body dynamics. (C) 2013 Elsevier Ltd. All rights reserved.
This study deals with the numerical prediction and experimental description of the flow-induced deformation in a rapidly convergent-divergent geometry which stands for a simplified tongue, in interaction with an expir...
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This study deals with the numerical prediction and experimental description of the flow-induced deformation in a rapidly convergent-divergent geometry which stands for a simplified tongue, in interaction with an expiratory airflow. An original in vitro experimental model is proposed, which allows measurement of the deformation of the artificial tongue, in condition of major initial airway obstruction. The experimental model accounts for asymmetries in geometry and tissue properties which are two major physiological upper airway characteristics. The numerical method for prediction of the fluid-structure interaction is described. The theory of linear elasticity in small deformations has been chosen to compute the mechanical behaviour of the tongue. The main features of the flow are taken into account using a boundary layer theory. The overall numerical method entails finite element solving of the solid problem and finite differences solving of the fluid problem. First, the numerical method predicts the deformation of the tongue with an overall error of the order of 20%, which can be seen as a preliminary successful validation of the theory and simulations. Moreover, expiratory flow limitation is predicted in this configuration. As a result, both the physical and numerical models could be useful to understand this phenomenon reported in heavy snorers and apneic patients during sleep. (c) 2007 Elsevier Ltd. All rights reserved.
This paper presents a fully coupled three-dimensional solver for the analysis of time-dependent fluid-structure interaction. A partitioned time-marching algorithm is employed for the solution to the time-dependent cou...
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This paper presents a fully coupled three-dimensional solver for the analysis of time-dependent fluid-structure interaction. A partitioned time-marching algorithm is employed for the solution to the time-dependent coupled discretized problem, thus enabling the use of highly developed, robust and well-tested solvers for each field. Coupling of the fields is achieved through a conservative transfer of information at the fluid-structure interface. An implicit coupling is achieved when the solutions to the fluid and structure subproblems are cycled at each time step until convergence is reached. The three-dimensional unsteady incompressible fluid is solved using a powerful implicit dual time-stepping technique with an explicit multistage Runga-Kutta time stepping in pseudo-time and arbitrary Lagrangian-Eulerian formulation for the moving boundaries. A finite element dynamic analysis of the highly deformable structure is carried out with a numerical strategy combining the implicit Newmark time integration algorithm with a Newton-Raphson second-order optimization method. Various test cases are presented for benchmarking and to demonstrate the potential applications of this method. Copyright (C) 2008 John Wiley & Sons, Ltd.
The unsteady interaction between an incompressible fluid and a deformable elastic structure is analyzed. An implicit numerical method is proposed. At each time step, the stresses at the fluid-structure interface are d...
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The unsteady interaction between an incompressible fluid and a deformable elastic structure is analyzed. An implicit numerical method is proposed. At each time step, the stresses at the fluid-structure interface are determined as a solution of an optimization problem. The modal decomposition of the structure equations leads to a problem to be solved with a reduced number of unknowns. The analytic gradient of the cost function was derived. Numerical tests validate the analytic derivative and show the behavior of a two-dimensional Navier-Stokes equations with plate-like model interaction. Copyright (C) 2007 John Wiley & Sons, Ltd.
A semi-implicit time advancing scheme for transient fluid-structure interaction problem is presented. At every time step, a least squares problem is solved by partitioned procedures, such that the continuity of the ve...
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A semi-implicit time advancing scheme for transient fluid-structure interaction problem is presented. At every time step, a least squares problem is solved by partitioned procedures, such that the continuity of the velocity as well as the continuity of the stress hold at the interface. During the iterative method for solving the optimization problem, the fluid mesh does not move, which reduces the computational effort. The stability of the algorithm is derived. The numerical results presented in this paper show that the computed solution is similar to the one obtained by the implicit algorithm, but the computational time is reduced. (C) 2008 Elsevier B.V. All rights reserved.
A numerical investigation of the dynamic fluid-structure interaction (FSI) of a yacht sail plan submitted to harmonic pitching is presented to address both issues of aerodynamic unsteadiness and structural deformation...
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A numerical investigation of the dynamic fluid-structure interaction (FSI) of a yacht sail plan submitted to harmonic pitching is presented to address both issues of aerodynamic unsteadiness and structural deformation. The FSI model - Vortex Lattice Method fluid model and Finite Element structure model - have been validated with full-scale measurements. It is shown that the dynamic behaviour of a sail plan subject to yacht motion clearly deviates from the quasi-steady theory. The aerodynamic forces presented as a function of the instantaneous apparent wind angle show hysteresis loops, suggesting that some energy is exchanged by the system. The area included in the hysteresis loop increases with the motion reduced frequency and amplitude. Comparison of rigid versus soft structures shows that FSI increases the energy exchanged by the system and that the oscillations of aerodynamic forces are underestimated when the structure deformation is not considered. Dynamic loads in the fore and aft rigging wires are dominated by structural and inertial effects. This FSI model and the obtained results may be useful firstly for yacht design, and also in the field of auxiliary wind assisted ship propulsion, or to investigate other marine soft structures. (c) 2013 Elsevier Ltd. All rights reserved.
In this study, we developed a finite element fluid-structure interaction model to understand the deformation and failure mechanisms of both monolithic and sandwich composite panels. A new failure criterion that includ...
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In this study, we developed a finite element fluid-structure interaction model to understand the deformation and failure mechanisms of both monolithic and sandwich composite panels. A new failure criterion that includes strain-rate effects was formulated and implemented to simulate different damage modes in unidirectional glass fiber/matrix composites. The laminate model uses Hashin's fiber failure criterion and a modified Tsai-Wu matrix failure criterion. The composite moduli are degraded using five damage variables, which are updated in the post-failure regime by means of a linear softening law governed by an energy release criterion. A key feature in the formulation is the distinction between fiber rupture and pull-out by introducing a modified fracture toughness, which varies from a fiber tensile toughness to a matrix tensile toughness as a function of the ratio of longitudinal normal stress to effective shear stress. The delamination between laminas is modeled by a strain-rate sensitive cohesive law. In the case of sandwich panels, core compaction is modeled by a crushable foam plasticity model with volumetric hardening and strain-rate sensitivity. These constitutive descriptions were used to predict deformation histories, fiber/matrix damage patterns, and inter-lamina delamination, for both monolithic and sandwich composite panels subjected to underwater blast. The numerical predictions were compared with experimental observations. We demonstrate that the new rate dependent composite damage model captures the spatial distribution and magnitude of damage significantly more accurately than previously developed models. (C) 2013 Elsevier Ltd. All rights reserved.
A three-dimensional analytic model involving products of angular and radial Mathieu functions is developed for the exact free vibration analysis and transient acousto-structural response of two parallel elliptical pla...
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A three-dimensional analytic model involving products of angular and radial Mathieu functions is developed for the exact free vibration analysis and transient acousto-structural response of two parallel elliptical plates, coupled with an internal bounded inviscid and compressible fluid medium, and under general external transverse loads of arbitrary temporal and spatial variations. Extensive numerical data are presented in an orderly fashion for the first ten symmetric/anti-symmetric system natural frequencies as a function of fluid layer thickness parameter for selected plate aspect ratios. Also, the occurrences of frequency veering phenomena between various modes of the same symmetry group and the interchange of associated mode shapes in the veering region are noted and discussed. Moreover, selected fluid-coupled structural deformation mode shapes are presented in vivid graphical form and the issue of mode localization is examined. The Laplace transform with respect to the time variable is subsequently invoked and a linear system of coupled algebraic equations is ultimately obtained, which is truncated and then solved by implementing Durbin's Laplace inversion algorithm accompanied with special solution convergence enhancement techniques for eradication of spurious oscillations (Gibbs' phenomenon). Numerical simulations are conducted for the displacement time histories of water-coupled double aluminum plates of selected aspect ratios and fluid depths, subjected to external loads of practical interest (i.e., an impulsive point load, a concentrated pulse load, and a uniformly distributed blast load). Validity of the results is established through computations made by using a commercial finite element package as well as by comparison with the data available in literature. (C) 2013 Elsevier Ltd. All rights reserved.
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