scholarly journals Two-Way Fluid-Structure Coupling in Vibration and Damping Analysis of an Oscillating Hydrofoil

2014 ◽  
Author(s):  
T. Liaghat ◽  
F. Guibault ◽  
L. Allenbach ◽  
B. Nennemann
Keyword(s):  
Fluid Structure Interaction ◽  
Mesh Size ◽  
Main Concern ◽  
Time Step ◽  
Flowing Fluid ◽  
Fluid Structure ◽  
Analysis And Design ◽  
Structure Interaction ◽  
Hydrodynamic Damping ◽  
Hydraulic Machines

Fluid-structure interaction (FSI) and unavoidable vibrations are important characteristics in the operation of hydropower structures and must be taken into account in the analysis and design of such equipment. Hydrodynamic damping influences the amplitude of vibrations and is directly related to fatigue problems in hydraulic machines which are of great importance. The aim of this study is to investigate the coupled effects of flowing fluid on a simplified hydrofoil by using three-dimensional two-way fluid-structure interaction modeling, in order to determine its importance in predicting vibration amplitudes and damping. The effect of considering different flow velocities is also investigated in the present study. The results of this research are compared with those obtained from experiments done by ANDRITZ [1]. The influences of mesh size and time step are also studied. Our results indicate that considering FSI in predicting the frequencies of the fluctuating fluid forces in practical problems might be ignored if the main concern of the analysis is to check the possibility of resonance. However, FSI must be included in the modeling when we aim to predict the influence of the fluid on the damping behavior in the hydrofoil vibration.

Dynamic Analysis of the Joined-Wing Configuration in High-Altitude Long-Endurance Aircraft Using Fluid-Structure Interaction Model

2007 ◽  
Author(s):  
Prabu Ganesh Ravindren ◽  
Kirti Ghia ◽  
Urmila Ghia
Keyword(s):  
Finite Element ◽  
High Altitude ◽  
Fluid Structure Interaction ◽  
Structural Deformation ◽  
Time Step ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Joined Wing ◽  
Long Endurance

Recent studies of the joined-wing configuration of the High Altitude Long Endurance (HALE) aircraft have been performed by analyzing the aerodynamic and structural behaviors separately. In the present work, a fluid-structure interaction (FSI) analysis is performed, where the fluid pressure on the wing, and the corresponding non-linear structural deformation, are analyzed simultaneously using a finite-element matrix which couples both fluid and structural solution vectors. An unsteady, viscous flow past the high-aspect ratio wing causes it to undergo large deflections, thus changing the domain shape at each time step. The finite element software ANSYS 11.0 is used for the structural analysis and CFX 11.0 is used for the fluid analysis. The structural mesh of the semi-monocoque joined-wing consists of finite elements to model the skin panel, ribs and spars. Appropriate mass and stress distributions are applied across the joined-wing structure [Kaloyanova et al. (2005)], which has been optimized in order to reduce global and local buckling. The fluid region is meshed with very high mesh density at the fluid-structure interface and where flow separation is predicted across the joint of the wing. The FSI module uses a sequentially-coupled finite element equation, where the main coupling matrix utilizes the direction of the normal vector defined for each pair of coincident fluid and structural element faces at the interface [ANSYS 11.0 Documentation]. The k-omega turbulence model captures the fine-scale turbulence effects in the flow. An angle of attack of 12°, at a Mach number of 0.6 [Rangarajan et al. (2003)], is used in the simulation. A 1-way FSI analysis has been performed to verify the proper transfer of loads across the fluid-structure interface. The CFX pressure results on the wing were transferred across the comparatively coarser mesh on the structural surface. A maximum deflection of 16 ft is found at the wing tip with a calculated lift coefficient of 1.35. The results have been compared with the previous study and have proven to be highly accurate. This will be taken as the first step for the 2-way simulation. The effect of a coupled 2-way FSI analysis on the HALE aircraft joined wing configuration will be shown. The structural deformation history will be presented, showing the displacement of the joined-wing, along the wing span over a period of aerodynamic loading. The fluid-structure interface meshing and the convergence at each time step, based on the quantities transferred across the interface will also be discussed.

Fluid-Structure Interaction Approach for Numerical Investigation of a Flexible Hydrofoil Deformations in Turbulent Fluid Flow

2018 ◽  
Author(s):  
M. Benaouicha ◽  
S. Guillou ◽  
A. Santa Cruz ◽  
H. Trigui
Keyword(s):  
Fluid Flow ◽  
Numerical Model ◽  
Stokes Equations ◽  
Fluid Structure Interaction ◽  
Time Step ◽  
Fluid Structure ◽  
Turbulent Fluid Flow ◽  
Turbulent Fluid ◽  
Structure Interaction ◽  
Ale Formulation

The study deals with a 3D Fluid-Structure Interaction (FSI) numerical model of a rectangular cantilevered flexible hydrofoil subjected to a turbulent fluid flow regime. The structural response and dynamic deformations are studied by analyzing the oscillations frequencies and amplitudes, under a hydrodynamics loads. The obtained numerical results are confronted with experimental ones, for validation. The numerical model is performed in the same geometric, physical and material conditions as the experimental set-up carried out in a hydrodynamic tunnel. A polyacetal (POM) flexible hydrofoil NACA0015 with an angle of attack of 8° is considered to be immersed in a fluid flow at a Reynold number of 3 × 105. The structure is initially at rest and then moved by the action of the fluid flow. The numerical model is based on a strong coupling procedure for solving the Fluid-Structure Interaction problem. The Arbitrary Lagrangian-Eulerian (ALE) formulation of the Navier-Stokes equations is used and an anisotropic diffusion equation is solved to compute the fluid mesh velocity and position at each time step. The finite volume method is used for the numerical resolution of the fluid dynamics equations. The structure deformations are described by the linear elasticity equation which is solved by the finite elements method. The Fluid-Structure coupled problem is solved by using the partitioned FSI implicit algorithm. A good agreement between numerical and experimental results for the hydrodynamics coefficients and hydrofoil deformations, maximum deflection and frequencies is obtained. The added mass and damping are analyzed and then the FSI effect on the dynamic deformations of the structure is highlighted.

scholarly journals Three-Dimensional Simulation of Fluid–Structure Interaction Problems Using Monolithic Semi-Implicit Algorithm

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 94 ◽  
Author(s):  
Cornel Marius Murea
Keyword(s):  
Stokes Equations ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Arbitrary Lagrangian Eulerian ◽  
Time Step ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Dimensional Simulation ◽  
Updated Lagrangian

A monolithic semi-implicit method is presented for three-dimensional simulation of fluid–structure interaction problems. The updated Lagrangian framework is used for the structure modeled by linear elasticity equation and, for the fluid governed by the Navier–Stokes equations, we employ the Arbitrary Lagrangian Eulerian method. We use a global mesh for the fluid–structure domain where the fluid–structure interface is an interior boundary. The continuity of velocity at the interface is automatically satisfied by using globally continuous finite element for the velocity in the fluid–structure mesh. The method is fast because we solve only a linear system at each time step. Three-dimensional numerical tests are presented.

Offshore Platform Fluid Structure Interaction Simulation

2012 ◽  
Author(s):  
Ali Marzban ◽  
Murthy Lakshmiraju ◽  
Nigel Richardson ◽  
Mike Henneke ◽  
Guangyu Wu ◽  
...  
Keyword(s):  
Fluid Structure Interaction ◽  
Offshore Platform ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Structural Deformation ◽  
Fe Model ◽  
Cfd Analysis ◽  
Time Step ◽  
Fluid Structure ◽  
Structure Interaction

In this study a one-way coupled fluid-structure interaction (FSI) between ocean waves and a simplified offshore platform deck structure was modeled. The FSI model consists of a Volume of Fluid (VOF) based hydrodynamics model, a structural model and an interface to synchronize data between these two. A Computational Fluid Dynamics (CFD) analysis was used to capture the breaking wave and impact behavior of the fluid on the structure using commercially available software STAR-CCM+. A 3D Finite Element (FE) model of the platform deck developed in ABAQUS was used to determine the deflection of the structure due to hydrodynamic loads. Nonlinear material behavior was used for all structural parts in the FE model. Transient dynamic structural analysis and CFD analysis were coupled by transferring the CFD-predicted pressure distribution to the structural part in each time step using the co-simulation capabilities of STAR-CCM+ and ABAQUS. The one-way FSI model was applied to investigate the possible physical causes of observed wave damage of an offshore platform deck during a hurricane. It was demonstrated that with proper physical conditions/configurations, the FSI model could reproduce a structural deformation comparable to field measurement and provide valuable insight for forensic analysis.

Tackling FSI Simulation for FIV Problems in Tube Bundle Systems With POD Approach

2011 ◽  
Author(s):  
Marie Pomarede ◽  
Aziz Hamdouni ◽  
Erwan Liberge ◽  
Elisabeth Longatte ◽  
Jean-Franc¸ois Sigrist
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Tube Bundle ◽  
Fluid Structure Interaction ◽  
Flowing Fluid ◽  
Fluid Structure ◽  
Reduced Order ◽  
Structure Interaction ◽  
Flow Past ◽  
Steam Boilers

Tube bundles in steam boilers of nuclear power plants and nuclear on-board stokehold are known to be exposed to high levels of vibrations under flowing fluid. This coupled fluid-structure problem is still a challenge for engineers, first because of the difficulty to fully understand it, second because of the complexity for setting it up numerically. Although numerical techniques could help the understanding of such a mechanism, a complete simulation of a fluid past a whole elastically mounted tube bundle is currently out of reach for engineering purposes. To get round this problem, the use of a reduced-order model has been proposed with the introduction of the widely used Proper Orthogonal Decomposition (POD) method for a flow past a fixed structure [M. Pomare`de, E. Liberge, A. Hamdouni, E.Longatte, & J.F. Sigrist - Simulation of a fluid flow using a reduced-order modelling by POD approach applied to academic cases; PVP2010, July 18–22, Seattle]. Interesting results have been obtained for the reconstruction of the flow. Here a first step is to propose to consider the case of a flow past a fixed tube bundle configuration in order to check the good reconstruction of the flow. Then, an original approach proposed by Liberge (E. Liberge; POD-Galerking Reduction Models for Fluid-Structure Interaction Problems, PhD Thesis, Universite´ de La Rochelle, 2008) is applied to take into account the fluid-structure interaction characteristic; the so-called “multiphase” approach. This technique allows applying the POD method to a configuration of a flow past an elastically mounted structure. First results on a single circular cylinder and on a tube bundle configuration are encouraging and let us hope that parametric studies or prediction calculations could be set up with such an approach in a future work.

scholarly journals NUMERICAL SIMULATION OF FLUID-STRUCTURE INTERACTION BETWEEN FISHING WOBBLER AND WATER

2020 ◽  
pp. 665
Author(s):  
Miroslav Mijajlović ◽  
Sonja Vidojković ◽  
Dušan Ćirić ◽  
Dragan Marinković
Keyword(s):  
Fluid Structure Interaction ◽  
Computational Time ◽  
Structural Domain ◽  
Time Step ◽  
Water Stream ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Solid Bodies ◽  
Computer Resources ◽  
Mutual Structure

This paper deals with modeling, discretization, and numerical analysis of the two-way fluid-structure interaction between a fishing wobbler and a water stream. The structural domain is an assembly of several bodies that have multiple mutual structure-to-structure interactions. These interactions are mostly nonlinear contacts that significantly influence the time step used in simulations. As a result of these nonlinearities, the numerical solving of such a model requires significant computer resources and a long computational time. The paper also presents the creation and numerical simplifications of the model. However, the model remains very realistic. It is concluded that solving the structural domain in a model that retains the interaction between solid bodies is more computationally sensitive and more demanding than solving the fluid domain.

Analysis of Fluid-Structure Interaction by Means of Dynamic Unstructured Meshes

1998 ◽  
Vol 120 (4) ◽  
pp. 792-798 ◽  
Author(s):  
F. J. Blom ◽  
P. Leyland
Keyword(s):  
Euler Equations ◽  
Fluid Structure Interaction ◽  
Fluid Motion ◽  
Inviscid Flow ◽  
Euler Method ◽  
Time Step ◽  
Fluid Structure ◽  
Large Rotation ◽  
Structure Interaction ◽  
Naca0012 Airfoil

This paper presents a computational analysis on forced vibration and fluid-structure interaction in compressible flow regimes. A so-called staggered approach is pursued where the fluid and structure are integrated in time by distinct solvers. Their interaction is then taken into account by a coupling algorithm. The unsteady fluid motion is simulated by means of an explicit time-accurate solver. For the fluid-structure interaction problems which are considered here the effects due to the viscosity can be neglected. The fluid is hence modeled by the Euler equations for compressible inviscid flow. Unstructured grids are used to discretise the fluid domain. These grids are particularly suited to simulate unsteady flows over complex geometries by their capacity of being dynamically refined and unrefined. Dynamic mesh adaptation is used to enhance the computational precision with minimal CPU and memory constraints. Fluid-structure interaction involves moving boundaries. Therefore the Arbitrary Lagrange Euler method (ALE-method) is adopted to solve the Euler equations on a moving domain. The deformation of the mesh is controlled by means of a spring analogy in conjunction with a boundary correction to circumvent the principle of Saint Venant. To take advantage of the differences between fluid and structure time scales, the fluid calculation is subcycled within the structural time step. Numerical results are presented for large rotation, pitching oscillation and aeroelastic motion of the NACA0012 airfoil. The boundary deformation is validated by comparing the numerical solution for a flat plate under supersonic flow with the analytical solution.

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