Showing papers on "Added mass published in 2018"
TL;DR: In this paper, a novel method is proposed to mitigate the chatter of the thin-walled workpiece by submerging the milling system in viscous fluid, and the effect of viscous fluids on the effect on milling force coefficients is investigated.
57 citations
TL;DR: In this paper, the authors used the advanced CFD software STAR-CCM+ where the overset method is used so that the mesh local to the body moves within a stationary outer mesh.
49 citations
TL;DR: In this paper, the authors derived analytical solutions of hydrodynamic pressure and force on an elliptical hollow cylinder by assigning reasonable boundary conditions and by solving the Mathieu's differential equation in elliptical coordinate system.
43 citations
TL;DR: In this article, a model for the dynamic behavior of a deepwater drilling platform riser system under emergency evacuation conditions is developed, and the model is discretized in a finite element approach and solved using Newmark's method.
40 citations
TL;DR: In this paper, a new analytical model for the oblique incidence sound transmission loss prediction of baffled panels with multiple subwavelength sized membrane-type acoustic metamaterial (MAM) unit cells is proposed.
36 citations
TL;DR: In this paper, the hydrodynamic coefficients of multiple heave plates are studied for offshore structures to reduce heave responses in oscillating flows, and the added mass and drag coefficients for a single and double heave plate with circular, octagonal and square cross-sections are proposed to cover a wide range of application.
35 citations
TL;DR: In this paper, the authors presented an extensive validation of a fully nonlinear numerical wave tank for the simulation of complex fluid-structure interaction of moored floating structures, based on the Navier-Stokes/6-DOF solver, interDyMFoam.
34 citations
17 Jan 2018
TL;DR: The added mass concept can be validly applied to viscous flows, provided that the circulatory-force expression accounts for image vorticity as discussed by the authors, and the most appropriate physical interpretation of added mass is discussed.
Abstract: The added-mass concept can be validly applied to viscous flows, provided that the circulatory-force expression accounts for image vorticity. The relationship between added mass and image vorticity is explored, and the most appropriate physical interpretation of added mass is discussed.
32 citations
TL;DR: In this article, the authors provided an intuitive modeling and simulation approach to obtain the hydrodynamic damping and added mass coefficients of an open-frame ROV using computational fluid dynamic (CFD) approach in the preliminary design stage.
Abstract: The hydrodynamic damping and added mass of a remotely operated vehicle (ROV) are difficult to model. This paper provided an intuitive modeling and simulation approach to obtain the hydrodynamic damping and added mass coefficients of an open-frame ROV using computational fluid dynamic (CFD) approach in the preliminary design stage where extensive hydrodynamic test facilities are not available. The software MATLAB™, STAR CCM+™ and WAMIT™ are employed to compute the hydrodynamic damping coefficients and added mass coefficients of the ROV for control system design and virtual reality. Experimental validation for the heave and yaw responses in a water tank shows a close relation and insight to the simulation results for subsequent control system design.
31 citations
TL;DR: In this paper, a substructure method for analysis of the seismic response of an arbitrary shape of structure is presented, where the structure is idealized as a three-dimensional finite element model system.
30 citations
TL;DR: In this article, a mathematically-tractable framework was proposed to predict the rigid body motion and elastic deformation of a ship impacting the water surface in free fall. But the model was not applied to the water entry of compliant slender bodies.
TL;DR: In this article, the hydrodynamic coefficients were calculated using the towing tank experimental results of an inclined flexible cylinder undergoing VIV at five different inclination angles (a = 0°, 15°, 30°, 45° and 60°), where a denotes the inclination angle defined as the angle between the cylinder axis and the plane orthogonal to the oncoming fluid flow).
TL;DR: In this paper, the authors demonstrate efficient attenuation of flexural vibrations by attaching a simple inertial amplification mechanism to a slender elastic beam, which generates enhanced inertial forces between two attachment points, which effectively counteracts the elastic forces in the beam for certain anti-resonance frequencies.
Abstract: We demonstrate efficient attenuation of flexural vibrations by attaching a simple inertial amplification (IA) mechanism to a slender elastic beam. The mechanism generates enhanced inertial forces between two attachment points, which effectively counteracts the elastic forces in the beam for certain anti-resonance frequencies. These anti-resonances may be generated in the low-frequency range, even for a small added mass. Furthermore, the hybrid structures are shown to exhibit two neighbouring anti-resonance dips providing wide and deep attenuation regions in the frequency domain. The obtained numerical results are validated with the experimental data.
TL;DR: Numerical simulations confirm the predictions of the stability analysis even for complex problems, and show that the AMP algorithm remains stable, without sub-iterations, for light and even zero-mass three-dimensional rigid bodies of general shape.
TL;DR: In this paper, the authors investigate the consequences of flow-induced bending on the vortex-induced dynamics of slender cantilever cylinders, by means of numerical simulations, and find that the primary consequence of flowinduced bending is the inhibition of single mode lock-in, replaced by a multi-frequency response of the structure, and the reduction of the vibration amplitude, as a result of the broadening of the wake excitation spectrum and of the localization of the energy transfer due to the variations induced in the normal flow profile.
TL;DR: A novel coupling approach for discrete particle simulations using a lattice Boltzmann formulation of the generalized Navier-Stokes equations that promises efficient simulations suitable for high performance computing and is also applicable to non-dilute particulate systems.
Journal Article•
TL;DR: In this paper, the effects of added mass and fluid damping on a flapping membrane are quantified using a simple damped oscillator model, and an analytic model based on thin airfoil theory coupled with a membrane equation is developed to characterize the steady and unsteady aeroelastic behavior of compliant membrane wings under different conditions.
Abstract: We present a theoretical framework to characterize the steady and unsteady aeroelastic behaviour of compliant membrane wings under different conditions. We develop an analytic model based on thin airfoil theory coupled with a membrane equation. Adopting a numerical solution to the model equations, we study the effects of wing compliance, inertia and flapping kinematics on aerodynamic performance. The effects of added mass and fluid damping on a flapping membrane are quantified using a simple damped oscillator model. As the flapping frequency is increased, membranes go through a transition from thrust to drag around the resonant frequency, and this transition is earlier for more compliant membranes. The wake also undergoes a transition from a reverse von Karman wake to a traditional von Karman wake. The wake transition frequency is predicted to be higher than the thrust–drag transition frequency for highly compliant wings.
TL;DR: In this paper, slam-induced bending of wave-piercing catamarans in head seas is predicted by way of fluid–structure interaction simulations and it is shown that two-way interaction simulation is not needed for predicting the slam induced hull girder loads.
TL;DR: In this article, the frequency-domain and time-domain response of a floating ice shelf to wave forcing are calculated using the finite element method, where the boundary conditions at the front of the ice shelf, coupling it to the surrounding fluid, are written as a special non-local linear operator with forcing.
TL;DR: In this paper, the authors considered wave radiation and diffraction by a circular cylinder submerged below an ice sheet with a crack, and obtained the results for the added mass and damping coefficient as well as the exciting force.
Abstract: Wave radiation and diffraction by a circular cylinder submerged below an ice sheet with a crack are considered based on the linearized velocity potential theory together with multipole expansion. The solution starts from the potential due to a single source, or the Green function satisfying both the ice sheet condition and the crack condition, as well as all other conditions apart from that on the body surface. This is obtained in an integral form through Fourier transform, in contrast to what has been obtained previously in which the Green function is in the series form based on the method of matched eigenfunction expansion in each domain on both sides of the crack. The multipole expansion is then constructed through direct differentiation of the Green function with respect to the source position, rather than treating each multipole as a separate problem. The use of the Green function enables the problem of wave diffraction by the crack in the absence of the body to be solved directly. For the circular cylinder, wave radiation and diffraction problems are solved by applying the body surface boundary condition to the multipole expansion, through which the unknown coefficients are obtained. Extensive results are provided for the added mass and damping coefficient as well as the exciting force. When the cylinder is away from the crack, a wide spacing approximation method is used, which is found to provide accurate results apart from when the cylinder is quite close to the crack.
TL;DR: In this article, two sets of heave plate experiments are described, at varying scale, using the Morison equation, in which the hydrodynamic coefficients of added mass and drag are determined for each set of Oscillator and mini-WEC experiments.
Abstract: Wave energy converters (WECs) often employ submerged heave plates to provide reaction forces at depths below the level of wave motion. Here, two sets of heave plate experiments are described, at varying scale. First, the Oscillator uses a linear actuator to force laboratory scale (30.5-cm diameter) heave plates in sinusoidal motion. Second, the miniWEC buoy uses vessel wakes to force field scale (1.5-m diameter) heave plates in open water with realistic energy conversion (damping). The motion and forces are analyzed using the Morison equation, in which the hydrodynamic coefficients of added mass $C_M$ and drag $C_D$ are determined for each set of Oscillator and miniWEC experiments. Results show strong intracycle variations in these coefficients, yet constant hydrodynamic coefficients provide a reasonable reconstruction of the time series data. The two test scales are examined relative to the Keulegan–Carpenter number ( $\text{KC}$ ), Reynold's number ( $Re$ ), and Beta number ( $\beta$ ). The effects of asymmetric shape on hydrodynamic performance are found to be small.
TL;DR: In this paper, the authors proposed a new correlation to predict the drag coefficient calculated from the fluctuated motion with the added mass force and history force, which is indicative of a nonconstant bubble drag coefficient.
Abstract: The motion of single bubbles rising in 2-octanol solutions was investigated experimentally. By using a high-speed video system to follow the rising bubble, the sequences of the recorded frames were digitized and analyzed using image analysis software. The periodical fluctuation of the bubble terminal velocity was observed, which is indicative of a nonconstant bubble drag coefficient. Then, the measured drag coefficient was compared with correlations available in the literature. The comparison shows that these correlations cannot give fully satisfactory results in predicting the fluctuated drag coefficient. Using the extensive experimental data, the authors proposed a new correlation to predict the drag coefficient calculated from the fluctuated motion with the added mass force and history force included. In virtue of nonlinear curve fitting, the drag coefficient of the single bubble is correlated as a function of the Re number, Eo number, We number, and Mo number based on the equivalent bubble diameter. T...
TL;DR: In this article, a point-absorber wave energy converter (WEC) with a waterproof outer-floater and a built-in power take-off (BI-PTO) mechanism, named Dual-Resonance WEC (DR-WEC), was proposed and investigated by experiments and numerical simulations.
TL;DR: In this article, the effects of non-axisymmetric substructures on the low-frequency vibro-acoustic responses of a propeller-shafting-hull system are investigated.
TL;DR: In this article, the authors developed a linearized equivalent mechanical model and a fourth-order nonlinear multimodal model that are capable of accommodating the fluid drag and added mass that are generated by the paddles.
TL;DR: In this article, a semi-implicit coupling technique is presented which strongly couples the added mass term of the fluid (pressure stress) to the structure, while the remaining terms are only loosely coupled.
TL;DR: In this paper, the authors present the dynamic buckling behavior of spherical shell structures colliding with an obstacle block under the sea, where the effect of deep water has been considered as a uniform external pressure.
Abstract: This paper is the first to present the dynamic buckling behavior of spherical shell structures colliding with an obstacle block under the sea. The effect of deep water has been considered as a uniform external pressure by simplifying the effect of fluid–structure interaction. The calibrated numerical simulations were carried out via the explicit finite element package LS-DYNA using different parameters, including thickness, elastic modulus, external pressure, added mass, and velocity. The closed-form analytical formula of the static buckling criteria, including point load and external pressure, has been firstly established and verified. In addition, unprecedented parametric analyses of collision show that the dynamic buckling force (peak force), mean force, and dynamic force redistribution (skewness) during collisions are proportional to the velocity, thickness, elastic modulus, and added mass of the spherical shell structure. These linear relationships are independent of other parameters. Furthermore, it can be found that the max force during the collision is about 2.1 times that of the static buckling force calculated from the analytical formula. These novel insights can help structural engineers and designers determine whether buckling will happen in the application of submarines, subsea exploration, underwater domes, etc.
TL;DR: In this article, the added mass, damping, and stiffness of a submerged structure in a fluid are considered when evaluating the dynamic response of the submerged structure to added mass and damping.
Abstract: Fluid added mass, damping, and stiffness are highly relevant parameters to consider when evaluating the dynamic response of a submerged structure in a fluid. The prediction of these parameters for ...
TL;DR: The added mass force has a significant contribution to the total aerodynamic force of the flapping wings during and near the stroke reversals, and the shorter the stroke amplitude is, the larger the addedmass force becomes.
TL;DR: In this article, the hydrodynamic force coefficients for two side-by-side flexible cylinders with four spacing ratios were studied via an inverse analysis method based on the time-varying displacements obtained from experimental tests.