Added Mass Effect Research Articles

Investigation on pressure pulsation and modal behavior of the impeller in a nuclear reactor coolant pump

AbstractAs the unique rotating component, the impeller is the core component of a nuclear reactor coolant pump (RCP), the dynamic properties of the impeller are critical for the safe operation of the whole reactor. The purpose of this study was to shed comprehensive light on the pressure pulsation and modal properties of a scaled RCP impeller via experimental and numerical methods. The numerical model was validated by an experiment connecting the pressure pulsation signals at the diffuser inlet, and a good agreement was obtained between the numerical and experimental results. Pressure pulsation acting on the impeller's blade is mainly dominated by the impeller rotating frequency, the vane passing frequency, and the double blade‐passing frequency, and the pressure pulsation acting on the blade's pressure surface is more intense than on the suction surface. The modal properties were obtained via the modal test and numerical methods with the impeller suspended as a free body in the air and submerged inside water. The reduction in the impeller natural frequencies was between 31.63% and 37.77% for the corresponding mode shape due to the added mass effect of the fluid. Based on the pressure pulsation characteristics acting on the impeller and the natural frequency of the impeller, it is considered there is no risk of resonance in the impeller. Finally, it is expected that the present work can provide scientific guidance to avoid hydraulic resonance in nuclear reactor coolant pumps.

Study of Mosquito Aerodynamics for Imitation as a Small Robot and Flight in a Low-Density Environment.

In terms of their flight and unusual aerodynamic characteristics, mosquitoes have become a new insect of interest. Despite transmitting the most significant infectious diseases globally, mosquitoes are still among the great flyers. Depending on their size, they typically beat at a high flapping frequency in the range of 600 to 800 Hz. Flapping also lets them conceal their presence, flirt, and help them remain aloft. Their long, slender wings navigate between the most anterior and posterior wing positions through a stroke amplitude about 40 to 45°, way different from their natural counterparts (>120°). Most insects use leading-edge vortex for lift, but mosquitoes have additional aerodynamic characteristics: rotational drag, wake capture reinforcement of the trailing-edge vortex, and added mass effect. A comprehensive look at the use of these three mechanisms needs to be undertaken—the pros and cons of high-frequency, low-stroke angles, operating far beyond the normal kinematic boundary compared to other insects, and the impact on the design improvements of miniature drones and for flight in low-density atmospheres such as Mars. This paper systematically reviews these unique unsteady aerodynamic characteristics of mosquito flight, responding to the potential questions from some of these discoveries as per the existing literature. This paper also reviews state-of-the-art insect-inspired robots that are close in design to mosquitoes. The findings suggest that mosquito-based small robots can be an excellent choice for flight in a low-density environment such as Mars.

A high-fidelity numerical study on the propulsive performance of pitching flexible plates

In this paper, we numerically investigate the propulsive performance of three-dimensional pitching flexible plates with varying flexibility and trailing edge shapes. We employ our recently developed body-conforming fluid-structure interaction solver for our high-fidelity numerical study. To eliminate the effect of other geometric parameters, only the trailing edge angle is varied from 45° (concave plate), 90° (rectangular plate) to 135° (convex plate) while maintaining the constant area of the flexible plate. For a wide range of flexibility, three distinctive flapping motion regimes are classified based on the variation of the flapping dynamics: (i) low bending stiffness KBlow, (ii) moderate bending stiffness KBmoderate near resonance, and (iii) high bending stiffness KBhigh. We examine the impact of the frequency ratio f* defined as the ratio of the natural frequency of the flexible plate to the actuated pitching frequency. Through our numerical simulations, we find that the global maximum mean thrust occurs near f*≈1 corresponding to the resonance condition. However, the optimal propulsive efficiency is achieved around f* = 1.54 instead of the resonance condition. While the convex plate with low and high bending stiffness values shows the best performance, the rectangular plate with moderate KBmoderate is the most efficient propulsion configuration. To examine the flow features and the correlated structural motions, we employ the sparsity-promoting dynamic mode decomposition. We find that the passive deformation induced by the flexibility effect can help in redistributing the pressure gradient, thus, improving the efficiency and the thrust production. A momentum-based thrust evaluation approach is adopted to link the temporal and spatial evolution of the vortical structures with the time-dependent thrust. When the vortices detach from the trailing edge, the instantaneous thrust shows the largest values due to the strong momentum change and convection process. Moderate flexibility and convex shape help to transfer momentum to the fluid, thereby improving the thrust generation and promoting the transition from drag to thrust. The increase in the trailing edge angle can broaden the range of flexibility that produces positive mean thrust. The role of added mass effect on the thrust generation is quantified for different pitching plates and the bending stiffness. These findings are of great significance to the optimal design of propulsion systems with flexible wings.

Bubble cloud configuration effect on the added mass

Understanding the mechanisms that control the dynamics of bubble clouds is essential to many industrial processes in the energy and chemical realms. Due to the complexity of the two-phase flow configurations, modeling the physics of the phenomena driving the mixing of bubbles within a liquid matrix is still a major challenge. One of the weaknesses of most existing two-phase flow models is due to the incomplete handling of bubble dispersion. This difficulty comes from the fact that dispersion can be driven by numerous complex phenomena, such as turbulence, local pressure distribution, bubble to bubble interaction, etc. In this study, we introduce the effect of added mass fluctuations on the dispersion of small bubbles. Existing models based on the Euler–Euler approach do not take into account local flow variations due to bubble distributions. Therefore, these models do not correctly describe fine dispersion features. Solving the potential flow around N bubbles allows to take into account the effect of the added mass on bubble cloud distributions. To this aim, a complete added mass model, which includes local bubble configurations via the void fraction gradient, is developed. The void fraction gradient allows us to account for the asymmetry of the bubble cloud around a single central bubble. Consequently, the proposed model can only represent regular and irregular bubble cloud distributions. This methodology results in a more consistent consideration of the added mass effects as well as Meshchersky's force, which should be included in hydrodynamic two-phase flow models. The proposed approach can be implemented in Euler–Euler models intended to consider the dispersion of bubbles caused by the effect of added mass.

Numerical and experimental studies of heave damping and added mass of spar with heave plates using forced oscillation

Heave plates are widely used in floating offshore structures to reduce the heave motion by increasing heave damping and heave added mass, and these parameters are sensitive to the amplitude and frequency of heave motion. It is important to obtain the hydrodynamic parameters, namely, damping and added mass of the floater not only at its natural frequency, which can be obtained from free decay tests but also at other frequencies because the floater response is of interest over a wide range of amplitudes and frequencies. Forced oscillation tests in calm water can aid the investigation of these parameters at various motion frequencies and amplitudes. Heave damping and added mass of classic spar with heave plate are investigated in this study using experiments and numerical simulations of forced heave oscillation of a 1:100 scale model in calm water for various frequency-amplitude combinations. The least square method was used to determine the added mass and damping using three damping models, namely, linear, quadratic, and linear-plus-quadratic, and their applicability assessed. The effect of amplitude and frequency of oscillation on the parameters are discussed for various heave plate configurations with the aid of flow visualization from numerical simulations. Added mass effect is examined using flow visualization of the fluid acceleration field. The scale effect on the parameters is also addressed.

Modeling added mass effects on the vibrations of air-backed, pre-deformed membranes

The study of vibrations of air-backed structures in water is necessary across a range of engineering applications, from naval to civil engineering. Common to these applications is the presence of geometric curvatures in the structure, which are responsible for rich, three-dimensional fluid-structure interactions. Toward a first theoretical understanding of these phenomena, we focus on the vibrations of hydrostatically pre-deformed, air-backed membranes. Under the assumption that the mode shapes of the membrane are only marginally affected by the fluid, we put forward a staggered solution procedure that is amenable to mathematical treatment. First, we determine the mode shapes of the pre-deformed membrane in vacuum using von Kármán theory. Then, we employ these mode shapes as an input to the potential flow problem, which is solved through perturbation theory. The proposed approach allows for an analytical study of hydrodynamic forces on circular membranes as a function of their curvature, shedding light on the added mass effect associated with the inertia of the fluid. Our results indicate that the membrane curvature enhances the added mass effect, thereby reducing the fundamental frequency of the membrane. The increase in the added mass is ascribed to the increase in the volume of fluid displaced by the membrane and to the increase in the velocity of the induced fluid flow, which causes larger dynamic loading close to the center of the membrane. Our methodology offers critical insight into the physics of fluid-structure interactions in air-backed curved structures.

The One-Way FSI Method Based on RANS-FEM for the Open Water Test of a Marine Propeller at the Different Loading Conditions

This paper aims to assess a new fluid–structure interaction (FSI) coupling approach for the vp1304 propeller to predict pressure and stress distributions with a low-cost and high-precision approach with the ability of repeatability for the number of different structural sets involved, other materials, or layup methods. An outline of the present coupling approach is based on an open-access software (OpenFOAM) as a fluid solver, and Abaqus used to evaluate and predict the blade’s deformation and strength in dry condition mode, which means the added mass effects due to propeller blades vibration is neglected. Wherein the imposed pressures on the blade surfaces are extracted for all time-steps. Then, these pressures are transferred to the structural solver as a load condition. Although this coupling approach was verified formerly (wedge impact), for the case in-hand, a further verification case, open water test, was performed to evaluate the hydrodynamic part of the solution with an e = 7.5% average error. A key factor for the current coupling approach is the rotational rate interrelated between two solution domains, which should be carefully applied in each time-step. Finally, the propeller strength assessment was performed by considering the blades’ stress and strain for different load conditions.

Experimental Evaluation of Dynamic Characteristics of Circular Arc Spring Dampers for Rotating Machinery

Abstract This study presents an experimental evaluation of the dynamic characteristics of the circular arc spring damper (CASD), which attenuates the vibration of rotating machinery. The CASD is a novel type of fluid film damper that has two or more arc-shaped beams and dual slits (radial clearances) formed by wire electric discharge machining (WEDM). A major advantage of CASDs over conventional squeeze film dampers (SFDs) with squirrel-cage springs is their compactness and low weight. The concept of CASDs was originally proposed by Kanki et al. (2005). However, the basic characteristics of this type of damper, including the influence of the geometries, added mass coefficients, and cross-coupled terms of dynamic coefficients have not been investigated. To clarify these characteristics, a series of excitation tests was conducted on three types of CASDs to identify their dynamic coefficients. The features of the newly developed test rig and experimental results are presented in this study. Tested dampers have the same outer diameter (160 mm) and damper width (44 mm) but different arc patterns (2-arc or 4-arc) and radial clearances (about 0.3 or 1.2 mm). All dampers were tested in both open-end and end-sealed configuration. The influence of the end-seal clearances (about 0.1–0.4 mm) was also examined. The following results were obtained: (1) 4-arc type CASDs have greater damping than that of 2-arc types; (2) CASDs have a considerable amount of added mass coefficients, especially in the end-sealed condition; (3) smaller end-seal clearances make the damping and added-mass coefficients significantly larger; (4) A large level of damping can be produced with dashpot configuration (large radial clearances and small end-seal clearances), though the added-mass effect becomes more prominent; (5) cross-coupled terms are very small in centered/small amplitude motion. These new findings can be utilized for the design and application of CASDs to real rotating machineries.

The Importance of Flapping Kinematic Parameters in the Facilitation of the Different Flight Modes of Dragonflies

To better understand dragonflies’ remarkable flapping wing aerodynamic performance, we measured the kinematic parameters of the wings in two different flight modes (Normal Flight Mode (NFM) and Escape Flight Mode (EFM)). When the specimens switched from normal to escape mode the flapping frequency was invariant, but the stroke plane of the wings was more horizontally inclined. The flapping of both wings was adjusted to be more ventral with a change of the pitching angle that resulted in a larger angle of attack during downstroke and smaller during upstroke to affect the flow directions and the added mass effect. Noticeably, the phasing between the fore and hind pair of wings varies between two flight modes, which affects the wing-wing interaction as well as body oscillations. It is found that the momentum stream in the wake of EFM is qualitatively different from that in NFM. The change of the stroke plane angle and the varied pitching angle of the wings diverts the momentum downwards, while the smaller flapping amplitude and less phase difference between the wings compresses the momentum stream. It seems that in order to achieve greater flight maneuverability a flight vehicle needs to actively control positional angle as well as the pitching angle of the flapping wings.

A method for identification of analyte concentration in aqueous solution by using a mistuned fluid-structure coupled vibration

In this paper, a method is presented for measurement of analyte concentration in an aqueous solution, using the magnitude change of frequency response induced by mistuned fluid-structure coupled vibration of the suggested structure immersed in the solution. Firstly, the operating principle is explained by analyzing natural characteristics and mistuned responses of the suggested structure by using finite element method (FEM). Then added mass effect induced by the fluid-structure interaction is formulated, by which variations of the analyte concentration can be manifested into the change of the added mass acting on the suggested structure. Based on the operating principle, the resonant amplitudes of the structure are investigated under different fluid densities, and it shows much higher sensitivity than the frequency changes used in previous works. Lastly, the suggested structure is optimized and simulated for detecting glucose concentration at human blood glucose level and noticeable differences are observed for different glucose concentrations.

Ships Added Mass Effect on a Flexible Mooring Dolphin in Berthing Manoeuvre

This paper deals with the hydrodynamic effect of the ship on a flexible dolphin during a mooring manoeuvre. The hydrodynamic effect refers to the change in momentum of the surrounding fluid, which is defined by the concept of added mass. The main reason for the present study is to answer the question, “What is the effect of the added mass compared to the mass of the ship during the mooring procedure for a particular type of ship?” Measured angular frequencies of dolphin oscillations showed that the mathematical model can be approximated by the zero frequency limit. This simplifies the problem to some extent. The mooring is a pure rocking motion, and the 3D study is approximated by the strip theory approach. Moreover, the calculations were performed with conformal mapping using conformal Lewis mapping for the hull geometry. The fluid flow is assumed to be non-viscous, non-rotating and incompressible. The results showed that the additional mass effect must be taken into account when calculating the flexible dolphin loads.

Study on Added Mass Effect Caused by Collision of a Floating Body

Study on Added Mass Effect Caused by Collision of a Floating Body

Numerical simulation of 2-D fluid-structure interaction with a tightly coupled solver and establishment of the mooring model

In this study, a newly enhanced Fluid-Structure Interaction (FSI) model which incorporates mooring lines was used to simulate a floating structure. The model has two parts: a Computational Fluid Dynamics (CFD) model and a mooring model. The open-source CFD OpenFOAM® v1712 toolbox was used in the present study, and the convergence criteria and relaxation method were added to the computational procedure used for the OpenFOAM multiphase flow solver, interDyMFoam. A newly enhanced, tightly coupled solver, CoupledinterDyMFoam, was used to decrease the artificial added mass effect, and the results were validated through a series of benchmark cases. The mooring model, based on the finite element method, was established in MATLAB® and was validated against a benchmark analytical elastic catenary solution and numerical results. Finally, a model which simulates a floating structure with mooring lines was successfully constructed by connecting the mooring model to CoupledinterDyMFoam.

Effects of Time-Varying Fluid on Dynamical Characteristics of Cantilever Beams: Numerical Simulations and Experimental Measurements

In order to obtain the effects of time-varying fluid on dynamical characteristics of cantilever beams, this paper gives a comprehensive study of cantilever beams vibrating in a fluid with variable depth. The mathematical model of the cantilever beams in time-varying fluid is derived by combining Euler–Bernoulli beam theory and velocity potential theory, and the influence of the time-varying fluid is discussed. Then, a two-way fluid-structure interaction (FSI) numerical simulation procedure is proposed to calculate the transient responses of the beam. The validity and accuracy are verified according to the comparison among theoretical analysis, numerical simulations, and experimental measurements. Results show that, besides the added mass effect, a damping-like term is also induced due to the motion of the fluid, which is proportional to the moving velocity of the fluid. Both the added mass and the added damping increase with the increment of the width of the beam. The surrounding fluid near the free end affects the beam more significantly. As a negative damping is caused while the fluid decreases, resulting in a much slower decay of the time responses. Therefore, the added damping should not be neglected in the analysis of the FSI problems with time-varying fluid.

Dynamics and buckling loads for a vibrating damped Euler\u2013Bernoulli beam connected to an inhomogeneous foundation

In this paper, the dynamics and the buckling loads for an Euler–Bernoulli beam resting on an inhomogeneous elastic, Winkler foundation are studied. An analytical, asymptotic method is proposed to determine the stability of the Euler–Bernoulli beam for various types of inhomogeneities in the elastic foundation taking into account different types of damping models. Based on the Rayleigh variation principle, beam buckling loads are computed for cases of harmonically perturbed types of inhomogeneities in the elastic foundation, for cases of point inhomogeneities in the form of concentrated springs in the elastic foundation, and for cases with rectangular inclusions in the elastic foundation. The investigation of the beam dynamics shows the possibility of internal resonances for particular values of the beam rigidity and longitudinal force. Such types of resonances, which are usually typical for nonlinear systems, are only possible for the beam due to its inhomogeneous foundation. The occurrence of so-called added mass effects near buckling instabilities under the influence of damping have been found. The analytical expressions for this “added mass” effect have been obtained for different damping models including space hysteresis types. This effect arises as a result of an interaction between the main mode, which is close to instability, and all the other stable modes of vibration.

A loosely-coupled scheme for the flow-induced flapping problem of two-dimensional flexible plate with strong added-mass effect

Loosely-coupled scheme is extensively used to simulate fluid-structure interaction (FSI) problems due to its efficiency. However, it meets the numerical difficulty of instability in the strong added-mass scenario. In this paper, a loosely-coupled scheme is proposed for solving the flow-induced flapping problem of two-dimensional (2D) flexible plate with strong added-mass effect. Specifically, finite volume method is used to simulate the flow field and mode superposition method is applied to calculate the structure field. In order to avoid the added-mass induced numerical instability, governing equation of the flexible plate is modified with added mass being added to its both sides. First of all, this proposed scheme is validated through simulating hydrodynamic response of a single cantilever flexible plate in uniform flows. Then, to study the stability of the proposed scheme, the flow-induced oscillations of a cantilever flexible plate with various low mass ratios and strong added-mass effects are studied. The critical stability boundary of the flapping dynamics of a cantilever flexible plate is also presented. Finally, the proposed scheme is applied to simulate the hydrodynamic behaviors of two parallel plates in uniform flows. Two distinct flapping dynamics models (in-phase and out-of-phase oscillations) are obtained and their corresponding flow details are illustrated.

Stochastic resonance induced performance enhancement of MEMS cantilever biosensors

This paper presents an application of stochastic resonance for improving the performance of micro-electromechanical system (MEMS) cantilever biosensors operating in liquid media. The hydrodynamic influences in liquid media that consist of added mass effect, viscous damping and squeeze film damping deteriorate the Q-factor of cantilever oscillator sensors so much that their operation under fluid-immersed conditions becomes impractical. The stochastic resonance can be produced by the addition of noise in two ways: one, by direct transfer of noise energy through some nonlinear interaction process with the oscillator; and second, by making intrinsic parameters of the oscillator noisy. In this work, we are concerned with the second approach where MEMS controlled feedback oscillator is the biosensor. The cantilever motion is modeled as a damped harmonic oscillator with its natural frequency and damping coefficient parameters made noisy for generating stochastic resonance. Both the frequency and the damping noises generate stochastic resonance in the oscillator amplitude; however, the damping noise generates an additional resonance effect in the oscillator phase. The latter creates the possibility for improving Q-factor against the detrimental influences of hydrodynamic loading. This is a novel feature, which we explore in this paper for maintaining self-sustained cantilever oscillations in a liquid medium and for enhancing biosensor performance. The biosensor model takes into account the circuit loading effect and the influence of cantilever noise in hydrodynamic environment as well. The analytical relations for mass sensitivity and limit of detection have been obtained. The limit of detection is found to be inversely proportional to where and denote cantilever amplitude and Q-factor, respectively. That means the phase stochastic resonance produced by the addition of damping noise lowers the limit of detection by enhancing both and . A prototype theoretical analysis with a Si-MEMS cantilever ( μm3 dimensions and 10 μm gap from boundary wall) oscillator sensor in aqueous medium shows 2 to 3 orders of magnitude enhancement in the Q-factor and 4 to 5 orders of magnitude improvement in the limit of mass detection.

Dynamic behavior of a deformable bubble rising near a vertical wire-mesh in the quiescent water

Because wire-meshes have a great potential application for designing high-efficient heat and mass transfer systems, a deformable bubble of Re ~ 800 rising in still tap-water near a vertical mesh of different porosity is studied using a high-speed shadowgraphy apparatus including two mutually perpendicular projections. We focus on the effect of the boundary conditions with three types of meshes (Mesh-L, Mesh-M, and Mesh-S) and initial wall distance s* on the dynamic behavior of the bubbles rising by the presence of the meshes. The dynamic parameters, shape oscillation, and energy components are discussed, compared to the cases of the free-rising bubbles and that near impermeable walls. Results show that the near-mesh bubble always travels within a three-dimensional spiral trajectory at different initial wall distances, similar to the corresponding free-spiraling bubble. The mesh-bubble collisions only happen on the Mesh-L and Mesh-M, at the smallest initial distance s* = 0.11, due to their lower pressure drop before and after the mesh as a liquid through it and causing the stronger added mass effect on the bubbles. Compared to the no-slip wall, the mesh, as a slippery boundary condition of non-zero wall-normal velocity, has insignificant interference on the bubble wake, suppressing the symmetric vortex shedding and then the transition of the bubble path from spiraling into zigzagging. The interference of the mesh can lead to the transition and obvious fluctuation in the characteristic frequencies of the lateral migration, velocity, and symmetric shape-oscillation. In terms of energy, the horizontal momentum components of a near-mesh rising bubble are transferred to each other to maintain the spiral motion. The absence of bubble-mesh collisions may explain why just the energy dissipation ED generated by Mesh-S changes slightly and maintains at a lower level at s* < 9.05, while ED caused by other walls or meshes cannot achieve this low level until s* > 4.58. It is expected that our findings will be helpful to predict or modify the near-mesh gas void-fraction distribution and to improve mass, heat transfer in related engineered systems.

New iterative and staggered solution schemes for incompressible fluid‐structure interaction based on Dirichlet‐Neumann coupling

SummaryIn the presence of strong added mass effects, partitioned solution strategies for incompressible fluid‐structure interaction are known to lack robustness and computational efficiency. A number of strategies have been proposed to address this challenge. However, these strategies are often complicated or restricted to certain problem classes and generally require intrusive modifications of existing software. In this work, the well‐known Dirichlet‐Neumann coupling is revisited and a new combined two‐field relaxation strategy is proposed. A family of efficient staggered schemes based crucially on a force predictor is formulated alongside the classical iterative approach. Both methodologies are rigorously analyzed on the basis of a linear model problem derived from a simplified fluid‐conveying elastic tube. The investigation suggests that both the robustness and the efficiency of a partitioned Dirichlet‐Neumann coupling scheme can be improved by a relatively small nonintrusive modification of a standard implementation. The relevance of the model problem analysis for finite element‐based computational fluid‐structure interaction is demonstrated in detail for a submerged cylinder subject to an external force.

Modelling capsizing icebergs in the open ocean

Summary At near-grounded glacier termini, calving can lead to the capsize of kilometre-scale (i.e. gigatons) unstable icebergs. The transient contact force applied by the capsizing iceberg on the glacier front generates seismic waves that propagate over teleseismic distances. The inversion of this seismic signal is of great interest to get insight into actual and past capsize dynamics. However, the iceberg size, which is of interest for geophysical and climatic studies, cannot be recovered from the seismic amplitude alone. This is because the capsize is a complex process involving interactions between the iceberg, the glacier and the surrounding water. This paper presents a first step towards the construction of a complete model, and is focused on the capsize in the open ocean without glacier front nor ice-mélange. The capsize dynamics of an iceberg in the open ocean is captured by computational fluid dynamics (CFD) simulations, which allows assessing the complexity of the fluid motion around a capsizing iceberg and how far the ocean is affected by iceberg rotation. Expressing the results in terms of appropriate dimensionless variables, we show that laboratory scale and field scale capsizes can be directly compared. The capsize dynamics is found to be highly sensitive to the iceberg aspect ratio and to the water and ice densities. However, dealing at the same time with the fluid dynamics and the contact between the iceberg and the deformable glacier front requires highly complex coupling that often goes beyond actual capabilities of fluid-structure interaction softwares. Therefore, we developed a semi-analytical simplified fluid-structure model (SAFIM) that can be implemented in solid mechanics computations dealing with contact dynamics of deformable solids. This model accounts for hydrodynamic forces through calibrated drag and added-mass effects, and is calibrated against the reference CFD simulations. We show that SAFIM significantly improves the accuracy of the iceberg motion compared with existing simplified models. Various types of drag forces are discussed. The one that provides the best results is an integrated pressure-drag proportional to the square of the normal local velocity at the iceberg’s surface, with the drag coefficient depending linearly on the iceberg’s aspect ratio. A new formulation based on simplified added-masses or computed added-mass proposed in the literature, is also discussed. We study in particular the change of hydrodynamic-induced forces and moments acting on the capsizing iceberg. The error of the simulated horizontal force ranges between 5 and 25 per cent for different aspect ratios. The added-masses affect the initiation period of the capsize, the duration of the whole capsize being better simulated when added-masses are accounted for. The drag force mainly affects the amplitude of the fluid forces and this amplitude is best predicted without added-masses.