scholarly journals Fluid–structure interaction-induced oscillation of flexible structures in laminar and turbulent flows

2013 ◽  
Vol 715 ◽  
pp. 537-572 ◽  
Author(s):  
Jorge Pereira Gomes ◽  
H. Lienhart
Keyword(s):  
Turbulent Flows ◽  
Fluid Structure Interaction ◽  
Flexible Structures ◽  
Reynolds Numbers ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Flow Disturbances ◽  
Oscillation Modes ◽  
Excited Oscillation ◽  
Excitation Mechanisms

AbstractSelf-excitation of the motion of a structure has become a prominent aspect of engineering projects over recent years as designers are using materials at their limits, causing structures to become progressively lighter, more flexible and, therefore, prone to vibrate. Stimulated by the increasing interest in fluid–structure interaction (FSI) problems, this study investigated the instability and consequent FSI-induced self-excited oscillation of flexible structures in uniform flows at Reynolds numbers between $10$ and $1. 69\times 1{0}^{5} $. The investigations were performed in both water and a highly viscous syrup ($\nu = 1. 64\times 1{0}^{- 4} ~{\mathrm{m} }^{2} ~{\mathrm{s} }^{- 1} $) and considered three structures of different geometries. The results were conclusive in showing that the motion of the structure was characterized by a sequence of oscillation modes as a function of the characteristics of the structure and flow properties. In addition, it was possible to identify the self-excitation mechanisms as being of the instability-induced excitation (IIE) or movement-induced excitation (MIE) types. IIE was observed to be the most dominant mechanism of excitation at lower velocities and it was defined by a direct relation between the flow fluctuation and natural frequencies of the structure. For that reason, IIE was strongly determined by the geometry of the front body of the structure. At higher velocities, the amplitudes of the flow disturbances generated by the structure movement increased and excitations of the MIE type became predominant for all structures. The MIE mechanism was found to be weakly influenced by the shape of the structure but very sensitive to its dynamic characteristics and to the properties of the fluid, especially the Reynolds number.

Multi-Scale Fluid-Structure Interaction Simulations Based on Mesoscopic Approaches

2014 ◽  
Author(s):  
Todd H. Weisgraber ◽  
Stuart D. C. Walsh ◽  
Kostas Karazis ◽  
Dennis Gottuso
Keyword(s):  
Turbulent Flows ◽  
Adaptive Mesh Refinement ◽  
Fluid Structure Interaction ◽  
Adaptive Mesh ◽  
Dynamics Modeling ◽  
Spacer Grid ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Numerical Effort ◽  
High Reynolds

Many challenging fluid-structure interaction problems in nuclear engineering remain unresolved because current CFD methodologies are unable to manage the number of computational cells needed and/or the difficulties associated with meshing changing geometries. One of the most promising recent methodologies for fluid dynamics modeling is the lattice-Boltzmann method — an approach that offers significant advantages over classical CFD methodologies by 1) greatly reducing meshing requirements, 2) offering great scalability, and 3) through relative ease of code parallelization. While LBM often requires increased numerical effort compared to other methods, this can be dramatically reduced by combining LBM with Adaptive Mesh Refinement (LB-AMR). This study describes an ongoing collaboration investigating nuclear fuel-assembly spacer grid performance. The LB-AMR method, used to simulate the flow field around a specific spacer grid design, is capable of describing turbulent flows for high Reynolds numbers, revealing rich flow dynamics in good qualitative agreement with experimental results. Prepared by LLNL under Contract DE-AC52-07NA27344.

Fluid transients and fluid-structure interaction in flexible liquid-filled piping

2001 ◽  
Vol 54 (5) ◽  
pp. 455-481 ◽  
Author(s):  
David C Wiggert ◽  
Arris S Tijsseling
Keyword(s):  
Fluid Structure Interaction ◽  
Mechanical Action ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Piping Systems ◽  
Safety And Reliability ◽  
Fluid Transients ◽  
Excitation Mechanisms ◽  
Support Mechanisms ◽  
Numerical And Analytical Methods

Fluid-structure interaction in piping systems (FSI) consists of the transfer of momentum and forces between piping and the contained liquid during unsteady flow. Excitation mechanisms may be caused by rapid changes in flow and pressure or may be initiated by mechanical action of the piping. The interaction is manifested in pipe vibration and perturbations in velocity and pressure of the liquid. The resulting loads imparted on the piping are transferred to the support mechanisms such as hangers, thrust blocks, etc. The phenomenon has recently received increased attention because of safety and reliability concerns in power generation stations, environmental issues in pipeline delivery systems, and questions related to stringent industrial piping design performance guidelines. Furthermore, numerical advances have allowed practitioners to revisit the manner in which the interaction between piping and contained liquid is modeled, resulting in improved techniques that are now readily available to predict FSI. This review attempts to succinctly summarize the essential mechanisms that cause FSI, and present relevant data that describe the phenomenon. In addition, the various numerical and analytical methods that have been developed to successfully predict FSI will be described. Several earlier reviews regarding FSI in piping have been published; this review is intended to update the reader on developments that have taken place over the last approximately ten years, and to enhance the understanding of various aspects of FSI. There are 123 references cited in this review article.

Aerodynamic Damping and Fluid-Structure Interaction of Blast Loaded Flexible Structures

2011 ◽  
Vol 82 ◽  
pp. 491-496
Author(s):  
Martien Teich ◽  
Norbert Gebbeken ◽  
Martin Larcher
Keyword(s):  
Dynamic Response ◽  
Fluid Structure Interaction ◽  
Flexible Structures ◽  
Blast Loads ◽  
Damping Term ◽  
Damping Force ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Aerodynamic Damping ◽  
Compliant Systems

This paper analyses the e ects of air-structure interaction of systems subjectedto weak blast loads. While these coupling e ects are negligible for typical steel or concretestructures, they may dominate the dynamic response of lighter and more exible (compliant)systems like membranes, blast curtains or cable facades. For these light and exible systems,a classical decoupled analysis, i.e., neglecting the inuence of the surrounding air, might sig-ni cantly overestimate the deections and strains. However, we show that the coupling e ectscan be accounted for by basically adding a viscous aerodynamic damping force. We discussand compare two approaches how to obtain the aerodynamic damping term. With decreasingstructural sti ness and mass, the damping contribution of air increases signi cantly. The resultsof Hydrocode simulations are presented, and an outlook into further areas of research is given.

scholarly journals Investigation of Fluid-Structure Interaction Induced Bending for Elastic Flaps in a Cross Flow

2020 ◽  
Vol 10 (18) ◽  
pp. 6177 ◽  
Author(s):  
Tayyaba Bano ◽  
Franziska Hegner ◽  
Martin Heinrich ◽  
Ruediger Schwarze
Keyword(s):  
Present Model ◽  
Fluid Structure Interaction ◽  
Flexible Structures ◽  
Three Dimensional ◽  
Cross Flow ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Numerical Investigations ◽  
Transient Simulations ◽  
Ansys Workbench

With the recent increase in the design of light and flexible structures, numerical investigations of fluid and structure together play a significant role in most engineering applications. Therefore, the current study presents an examination of fluid-structure interaction involving flexible structures. The problem is numerically solved by a commercial software ANSYS-Workbench. Two-way coupled three-dimensional transient simulations are carried out for the flexible flaps of different thicknesses in glycerin for a laminar flow and Reynolds number ranging from 3 < Re < 12. The bending line of the flaps is compared with experimental data for different alignments of the flaps relative to the fluid flow. The study reports the computation of the maximum tip-deflection and deformation of flaps fixed at the bottom and mounted normal to the flow. Additionally, drag coefficients for flexible flaps are computed and flow regimes in the wake of the flaps are presented. As well, the study gives an understanding on how the fluid response changes as the structure deforms and the model is appropriate to predict the behavior of thick and comparatively thinner flaps. The results are sufficiently encouraging to consider the present model for analyzing turbulent flow processes against flexible objects.

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