Flexible thin manufactures (sheets) are used in numerous engineering applications. In their manufacturing processes, the sheets are subjected to a fluid flow, and external disturbances can induce vibrations. The vibrations cause severe damage to the sheets. Therefore, an in-depth understanding of the vibration characteristics and excitation mechanism of a sheet in a fluid flow is essential. In this

The peak loads experienced by aircraft of all scales will typically be during gusts, turbulence or extreme manoeuvres. Understanding the aerodynamic response to these transient disturbances is therefore crucial, particularly when Leading-Edge Vortices (LEVs) occur. This fundamental study investigates the aerodynamic response to a wide range of transient plunging motions. The peak loads exhibited a

The structural motion and unsteady aerodynamic loads of a pitching airfoil model that features an actuated trailing edge flap are determined experimentally using a single measurement and data processing system. This integrated approach provides an alternative to the coordinated use of multiple measurement systems for simultaneous position and flow field measurements in large-scale fluid–structure interaction

Transverse vortex-induced vibration (VIV) of a two-dimensional, elliptic cylinder with various aspect ratios and stiffness is studied. The cylinder is elastically mounted and heated, and the flow direction is aligned with the direction of the thermal-induced buoyancy force. The transverse VIV can be suppressed as the thermal control parameter, the Richardson number (Ri), increases. Complete suppression

The drag–thrusttransition and wake structures of a pitching foil undergoing asymmetric sinusoidal oscillation are numerically investigated for foil thickness-based Strouhal number StD = 0.1–0.3 and amplitude ratio AD = 0.5–2.0. The asymmetry in the oscillation is introduced by making one half-stroke (e.g. from the lower extreme to the upper extreme) faster than the other. The results reveal that the

The study of the free swimming of undulating bodies in an otherwise quiescent fluid has always encountered serious difficulties for several reasons. When considering the full system, given by the body and the unbounded surrounding fluid, the absence of external forces leads to a subtle interaction problem dominated, at least at steady state conditions, by the equilibrium of strictly related internal

Damping screens are often installed within a tuned liquid damper (TLD) to increase the energy dissipation beyond what the sloshing liquid alone can provide. Many numerical models exist to study the response of a TLD; however, there are often associated limitations on fluid depth or excitation amplitude. The smoothed particle hydrodynamics (SPH) method can capture the fully nonlinear TLD response without

This paper reports the numerical results of the flow-induced vibration (FIV) of a trapezoidal cylinder with base length ratio of 0.3 placed at various flow orientations. Three typical attack angles (θ) of 0° (shorter base facing flow), 90° and 180° are examined in the computations that carried out for a reduced velocity range of Ur=2–20 at a low Reynolds number of 150. The vortex-induced vibration

In order to better understand the mechanism of panel flutter at low supersonic speeds, and to study the viscous effect on flutter boundary and flutter type, a coupled computational fluid dynamics and computational structure dynamics (CFD/CSD) methodology has been adopted. Detailed modal stability analyses have been conducted through the higher-order dynamic mode decomposition (HODMD) method, which

The control performance of a streamwise-oriented dielectric barrier discharge (DBD) plasma actuator, a set of plasma streamwise vortex generators (PSVGs), and a hybrid actuator of the plasma actuator and PSVGs on the reduction in bluff body flow separation, vortex-induced vibration (VIV), and wake fluctuation is experimentally investigated. Experiments are conducted in a low-speed and low-turbulence

Researchers, through time, have been conducted a series of theoretical and experimental measures on the glaze icing phenomena, but very few literatures can be found to quantify the effects of cylinder oscillation on the evolution of water films and ice shapes, and further to characterize aerodynamic characteristics during the glaze ice accretion process. A preliminary study is carried out to demonstrate

The dynamics of a cantilevered plate driven by a train of tangentially-advecting vortex rings is significantly impacted by two temporal parameters, namely the Strouhal number and the frequency ratio. The former relates the vortex ring advection time-scale to the fundamental period of the vibrating structure, while the latter relates the vortex production frequency to the structural fundamental frequency

For smart system designs based on elastic structures, buckled elastic sheets where both edges are clamped have gained significant attention as they exhibit interesting dynamic behaviors, namely, snap-through motion. In this study, the critical conditions and post-equilibrium responses of tandem buckled sheets under unbounded uniform flow are investigated experimentally to understand the mutual interactions

To investigate the characteristics of vortex-induced vibration (VIV) of the twin-box girder, we carried out the VIV wind tunnel tests. The VIV of the twin-box girder occurs in the range of 4.680≤ Ur ≤6.113, with the maximum dimensionless VIV displacement RMS(y)/D=0.03308 at reduced velocity at Ur=5.949. It is interesting that the VIV suddenly disappears at Ur=6.276 at the loading stage, and the large

We present results from two-dimensional numerical simulations based on Immersed Boundary Method (IBM) of a cylinder in uniform fluid flow attached to bistable springs undergoing Vortex-Induced Vibrations (VIV). The elastic spring potential for the bistable springs, consisting of two potential wells, is completely defined by the spacing between the potential minima and the depth of the potential wells

Flow-induced vibration of a flexible cylinder placed in the wake of a stationary rigid cylinder is studied, experimentally. The flexible cylinder with an aspect ratio of 47 and a mass ratio of 120 was held fixed at both ends and placed horizontally in the wake of the upstream rigid cylinder in the test-section of a subsonic wind tunnel. The dynamic response of the cylinder is studied in both the streamwise

This paper extends the Eulerian–Lagrangian–Lagrangian (ELL) method to solve the three-dimensional (3D) fluid–structure interaction (FSI) problems with flexible thin solids. The continuum-based (CB) shell element is adopted to model the flexible, thin-shell structure that undergoes large deformation. Several benchmarking problems, including a 3D cylinder-beam problem, vertical beam bending, and flapping

Water entry of vertical cylindrical shell is a nonlinear and unsteady process that involves the coupling of multiphase flow. In this paper, a numerical simulation of the water entry of vertical cylindrical shell is carried out with an objective to examine the physical mechanism of flow characteristics due to the effect of inner diameter. The numerical results are validated and verified against the

Numerical simulations of flow-induced vibration of a near-wall circular cylinder with a small gap (e) to diameter (D) ratio (e∕D=0.1) at low Reynolds numbers 55≤Re≤200 (based on the incoming velocity U∞ and the diameter D) are performed using a finite volume method by means of modified OpenFOAM codes. As the cylinder is very close to the wall, remeshing is regularly applied during the body oscillation

In this paper, a numerical method is presented to study the dynamic behaviour of an isotropic rectangular plate subjected to aerodynamic loads induced by parallel supersonic airflow. A finite element model, based on bi-dimensional polynomial displacement functions and linear Piston theory, is used to study the dynamic behaviour of the solid plate coupled with aerodynamic loads. The developed approach

The present paper is dedicated to the development of a numerical model for the water impact of two-dimensional (2D) and axisymmetric bodies with imposed motion. The work is a first step towards the implementation of a 2D+t procedure to be used for the analysis of aircraft ditching. The problem is investigated under the assumptions of an inviscid and incompressible fluid, which is modeled by a potential

A fluid–structure interaction (FSI) numerical model of the aortic valve was used to simulate and compare young and physiological aged operating conditions. The effect of normal ageing was considered by introducing alterations typically associated with senility: namely mild stiffening of the tissues and progressive dilation of the aortic chamber. The aim of this study is to provide a haemodynamic baseline

One of the major factors affecting the integrity of tube bundles in a steam generator undergoing excessive vibrations is fluidelastic instability. Currently, a comprehensive model for predicting fluidelastic instability in tube bundles under two-phase cross flow has not been developed. Accurate design guidelines on fluidelastic instability in tube bundles is crucial to avoid tube failure due to tube

An alternative solution to the flutter equation with a true damping representation is presented. The p-L method transforms the nonlinear eigenvalue problem into a linear generalized eigenvalue formulation by interpolating the nonlinear aerodynamic term with help of the Loewner and shifted-Loewner matrices, avoiding any kind of approximation. Subsequently an equivalent generalized state-space formulation

We use three-dimensional simulations to study the fluid–solid interactions between a highly-deflective biomimetic valve and a viscous fluid within a microfluidic channel, so as to guide the effective design of a biomimetic micropump. We study the steady state and dynamic behavior of the valve and fluid in response to applied fluid pressure gradients using a steady pressure drop and a trapezoidal pressure

Two types of wind-induced static torsional divergence of suspension bridge structures are addressed in this work in terms of analytic and numerical approaches. The vertical stiffness of a single cable, torsional stiffness of the cable system, bridge deck, and negative aerodynamic stiffness are analyzed via generalized models simplified by ignoring bridge towers’ deformation. It is found that the main

An efficient nonlinear time domain method computed higher order springing induced vertical bending vibrations of ships in waves. A weakly nonlinear time domain approach obtained the hydrodynamic response of the elastic hull girder, and a linear finite element model based on Timoshenko’s beam theory calculated its structural response. Coupling of the fully nonlinear stationary forward speed problem

Due to the increasing use of composite materials in high-speed planing craft prone to frequent slamming, the interaction between the structural response and hydrodynamic loading, hydroelasticity, must be considered. In this work, a V-shaped wedge model with 20° deadrise angle was vertically dropped into the calm water to simulate a typical hydroelastic slamming. With varied impact velocity and flexural

A new framework developed at CIRA to deal with Fluid–Structure Interaction phenomena in a partitioned approach has been developed. A multi-block structured flow solver for unsteady Navier–Stokes equations, UZEN, was updated and tightly coupled with the open-source FEM code CalculiX in a modular approach. The solvers are interfaced through the open source library preCICE (Bungartz, 2016), that takes

The monolithic classical and extended fluid-structural interaction water hammer models are based on the simplified ring hypothesis to characterize the structural radial response of the pipe under pressure. Recent work has shown that this approach predicts an unrealistic discontinuity in the pipe wall in the neighborhood of the pressure wave front. In order to remedy this limitation, the present study

The interaction between the first-order cnoidal wave and a concentric structure with dual-arc porous breakwaters is studied semi-analytically based on eigenfunction expansion. Both arcs of the breakwater are considered as thin shell structures and rigidly mounted on a flat sea bottom. The fluid domain is divided into an unbounded and two bounded sub-domains, within which the solutions are described

The fluid–structure interaction in a foil undergoing prescribed heave with passive pitching and flexibility about any pivot is formulated in the linear inviscid limit using a quartic approximation for the deflection. The resulting system of three algebraic equations is valid for arbitrary mass and stiffness distributions of the foil. The small pitching and deformation amplitudes result linearly from

The spinal cord (SC) is a tissue composed of white and gray matter that is permeated by capillary blood, venular blood and cerebrospinal fluid (CSF). It is surrounded by an annular cavity, called the subarachnoid space (SAS), within which the CSF exhibits a pulsatile laminar flow. Insights into the functioning of cerebrospinal fluid are expected to reveal the pathogenesis of severe neurological diseases

A 2D fluid–structure interaction (FSI) solver based on Smoothed Particle Hydrodynamics (SPH) and RKPM is established in this paper. Since we focus on the incompressible flow problem, the WCSPH is adopted to simulate the fluid. Meanwhile, the structure is modeled by the RKPM beam formulation, in which the plane strain hypothesis is adopted, and only a column of particles is needed to discretize the

The study of fluid–structure interaction (FSI) is a challengeable topic, which concerns a coupled system with consideration of not only the behaviors of the fluid and the structure, but also the interaction process between both. In this paper a coupled method is introduced to simulate FSI problems in two-dimensional (2-D) case. In this coupled method (2-D DDA-SPH), the smoothed particle hydrodynamics

As the desire for more flexible aircraft structures increases, so does the need to incorporate the intrinsic nonlinearities in their aeroelastic analyses. In that manner, it becomes essential to fully characterize the aeroelastic behavior and to investigate the effects that common external disturbances, such as atmospheric gust turbulence, might induce. In this work, an augmentation of the semi-empirical

In this study, we consider a simple system of water drops impacting cantilevered, circular fibers with velocity 1.0–2.4m∕s. The dynamics of the system are complicated because the motion of the drop and deflecting fiber at impact are highly coupled and the outcome is influenced by several continuous variables. The unpredictable dynamics of the system call for the use of computational tools that can

This paper presents the implementation and validation of a strongly coupled numerical model of a fully passive flapping foil turbine operating at a high Reynolds number. Thanks to a strong fluid–solid coupling strategy, the well known added-mass instability is mitigated while simulating a lightweight flapping foil. The numerical results are first validated in the case of a fixed foil undergoing static

This paper proposes a novel hybrid aeroelastic-pressure balance (HAPB) technique for the measurement of unsteady aerodynamic force on a galloping prism. HAPB wind tunnel tests were performed to simultaneously observe the unsteady aerodynamic force and galloping response of a test model. The amplitude-dependent nonlinear damping and stiffness of the HAPB system that include the non-wind-induced aerodynamic

A boundary element method (BEM) model is presented for wave forces on structures composed of solid and porous surfaces, where the porous surface can be subject to either a linear or quadratic pressure–velocity relation. In the case of the quadratic relation, the solutions to the radiation and diffraction problems cannot be superimposed to obtain a solution for body motions in waves. Instead, a solution

Flutter stability is a dominant design constraint of modern gas and steam turbines. To further increase the feasible design space, flutter-tolerant designs are currently explored, which may undergo Limit Cycle Oscillations (LCOs) of acceptable, yet not vanishing, level. Bounded self-excited oscillations are a priori a nonlinear phenomenon, and can thus only be explained by nonlinear interactions such

We study the response of a prism placed in flow and free to oscillate in the direction of flow (the inline direction) for different possible angles of attack. The tests were conducted in a water tunnel for a range of reduced velocities of 2.4 < U* < 5.8 and Reynolds numbers of 757 < Re < 1900, and over angles of attack of 0° ≤ α ≤ 45°, where α= 0° corresponded to the case where one of the square’s

This paper presents a parametric study of Vertical-Axis Turbines (VAT) equipped with chordwise-flexible blades. The objective of this study is to assess the possibility of increasing the efficiency of VATs by allowing passive foil deformations that take advantage of the periodically changing hydrodynamic conditions inherent to VATs. The study is carried out with numerical simulations based on a partitioned

Structure-Borne Traveling Waves (SBTWs) can replicate the combined undulatory and oscillatory motions utilized by body and/or caudal fin (BCF) aquatic swimmers. However, when SBTWs are generated in a dense fluid media, such as water, there is poor understanding of the Fluid–Structure Interactions (FSI). There is also limited understanding of how to achieve the full undulatory motions. This study demonstrates

A novel frequency domain numerical method for Very Large Floating Structure (VLFS) hydroelasticity is developed. The problem is formulated in the 2D ocean waveguide, featuring a realistic seabed bathymetry and the presence of inhomogeneous, elastic plates of varying thickness and negligible draft. An in vacuo modal expansion for the elastic body deflection, modelled as a structural plate, is employed

An experimental analysis of the vortex-induced vibration (VIV) of a catenary flexible riser with length to diameter ratio of 158, placed within a log-law sheared oncoming flow, is presented in this work. The experiments were conducted in a water flume with a wide reduced velocity range of 8.1–25.8, using the non-intrusive high-speed cameras to capture the in-plane and out-of-plane responses simultaneously

An in-duct device laid with acoustic liner is a popular noise control option for extensive ductworks carrying unsteady flow in various engineering applications. Besides the conventional absorptive liner, elastic panel liner backed by a cavity emerges as a promising alternative concept that has advantages in providing effective broadband reduction at low frequencies yet with significantly low fluid

Here, we investigate the static and dynamic response of semi-rigid cantilevers at various initial inclination angles (15° <α< 90°) and flexural rigidity (EI∼O(10−8) Pa-m4) to a uniform flow using a soap film tunnel. The vertical soap film tunnel produced uniform-flow Reynolds numbers 5×103

The steady and unsteady loads acting on a hydrofoil immersed in a turbulent boundary layer have been investigated. Measurements were performed in a cavitation tunnel in which the hydrofoil was mounted from the test section ceiling, via a 6-component force balance. Two NACA0012 hydrofoil models with trapezoidal planforms and aspect ratios of 2.4 and 1.2 were examined. The ceiling turbulent boundary

Recent experiments have shown that cones of intermediate apex angles display orientational stability with apex leading in flight. Here we show in experiments and simulations that analogous results hold in the two-dimensional context of solid wedges or triangular prisms in planar flows at Reynolds numbers Re∼102 to 103. Slender wedges are statically unstable with apex leading and tend to flip over or

Fluid–structure interaction (FSI) analysis is often highly computationally expensive, making it infeasible to conduct iterative aeroelastic design studies or rigorous optimizations. This work develops a new method for aeroelastic analysis that can be more efficient in the determination of final structure/fluid equilibrium configurations, especially during design studies where attributes of a structure

A new approach to build geometrically-nonlinear dynamic aeroelastic models is proposed that only uses information typically available in linear aeroelastic analyses, namely a generic (linear) finite-element model and frequency-domain aerodynamic influence coefficient matrices (AICs). Good computational efficiency is achieved through a two-step process: Firstly, a geometric reduction of the structure

A method for the efficient prediction of the course-keeping capability of sailing yachts in upwind sailing is presented, based on an integrated modular aero- and hydrodynamic model. The transient aerodynamic forces on the sails are calculated via the lifting surface theory and in particular the vortex lattice method for unsteady flows. The varying character of these forces due to sail shape deformation

Flexible sheets are used in many industrial applications. During their manufacturing processes, the coupling of the sheet motion and airflow causes flutter, which can result in severe quality defects. To prevent these defects, a detailed understanding of the fluttering mechanisms and characteristics is essential. In this study, wind-tunnel experiments and three-dimensional nonlinear flutter analysis

High-performance flutter and post-flutter predictions are critical in the design of a vast range of nonlinear fluid-structural systems. However, these predictions are often unfeasible due to their high computational cost. Moreover, traditional methods for flutter and post-flutter predictions are model intrusive and limited to one varying parameter at a time. To address these shortcomings, this paper

The strip theory in hydrodynamics has been widely used for predicting complex vortex induced vibrations (VIV) behind bluff bodies, but the question of how accurate such predictions are has not been addressed adequately before. In order to corroborate the application of strip theory in VIV, we present a comparative study between free mono-frequency vibrations of a long flexible cylinder in both uniform

In this paper, we present a numerical study on the transverse flow-induced vibration (FIV) of an elastically mounted sphere in the vicinity of a free surface at subcritical Reynolds numbers. We assess the interaction dynamics and the vibration characteristics of fully submerged and piercing spheres that are free to vibrate in the transverse direction. We employ the recently developed three-dimensional

A 1D/3D Finite-Volume coupling is proposed for the Euler/Homogeneous Equilibrium Model equations. The present approach is based on the Finite-Volume framework making it possible to tackle general equations of state. A special attention is given to the conservation of mass, momentum and energy at the common 1D/3D interface. For fluid–structure interaction induced by fast-transient phenomena occurring