A Three-Dimensional Plasticity and Momentum Model for Ship Resistance in Level Ice

1991 ◽  
Vol 113 (1) ◽  
pp. 53-60 ◽  
Author(s):  
C. H. Luk
Keyword(s):  
Numerical Methods ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Analytical Techniques ◽  
Full Scale ◽  
Momentum Balance ◽  
Ship Resistance ◽  
Plastic Limit Analysis ◽  
Level Ice ◽  
Ice Resistance

In this paper, a three-dimensional analysis is presented for calculating the level ice resistance for ships that have conventional hull forms. Comparisons with published ship resistance data and other analytical predictions are also provided. The present approach combines two analytical techniques: 1) plastic limit analysis is used to describe the ice failure mechanism and the associated ice velocity field; and 2) linear and angular momentum balances determine the average ice resistance for a ship. In the momentum balance, potential flow theory is used to describe the water motion induced by the icebreaking process. Existing methods for determining ship resistance in ice include numerical methods which depend on solutions of equations of motion that describe the dynamic interaction between the ice and the ship, and empirical methods which depend on model and full-scale icebreaker data to generate empirical correlations for ship resistance. The present results compare reasonably well with published model-scale and full-scale icebreaker data. Comparisons with predictions based on other numerical methods are also discussed.

Full Scale Measurement on Level Ice Resistance of Icebreaker

2011 ◽  
Author(s):  
Abdillah Suyuthi ◽  
Bernt J. Leira ◽  
Kaj Riska
Keyword(s):  
Water Resistance ◽  
Open Water ◽  
Full Scale ◽  
Ice Thickness ◽  
Total Resistance ◽  
Conservation Of Energy ◽  
Ship Resistance ◽  
Level Ice ◽  
Ice Resistance ◽  
Ship Speed

This paper presents results from the investigation of ship resistance on first year level ice in the Barent Sea. The basis for the work is the availability of full scale measurement data obtained on board of KV Svalbard in 2007. Measurements were made of the ice thickness, ship speed over ground in addition to setting power. The ice thickness was measured by means of an electromagnetic device, which enables careful selection of the time sequences for which level ice is present. By utilizing Newton II law and conservation of energy, the total resistance can be determined. The ice resistance in level ice was then obtained by subtracting the open-water resistance from the total resistance. The open-water resistance was measured when the ship was traveling in open water during the expedition. The relationship between the ship resistance and the ship speed over ground in level ice was finally obtained and compared with the Lindqvist formulation of estimation of ice resistance.

scholarly journals Formulation of Ice Resistance in Level Ice Using Double-Plates Superposition

2020 ◽  
Vol 8 (11) ◽  
pp. 870
Author(s):  
Liang Li ◽  
Qingfei Gao ◽  
Alexander Bekker ◽  
Hongzhe Dai
Keyword(s):  
Elastic Plate ◽  
Approximate Model ◽  
Ice Thickness ◽  
Full Scale Test ◽  
Ship Resistance ◽  
Bending Resistance ◽  
Level Ice ◽  
Scale Test ◽  
Coulomb Criterion ◽  
Ice Resistance

The estimation of ship resistance in ice is a fundamental area of research and poses a substantial challenge for the design and safe use of ships in ice-covered waters. In order to estimate the ice resistance with greater reliability, we develop in this paper an improved Lindqvist formulation for the estimation of bending resistance in level ice based on the superposition of double-plates. In the developed method, an approximate model of an ice sheet is firstly presented by idealizing ice sheeta as the combination of a semi-infinite elastic plate and an infinite one resting on an elastic foundation. The Mohr–Coulomb criterion is then introduced to determine the ice sheet’s failure. Finally, an improved Lindqvist formulation for estimation of ice resistance is proposed. The accuracy of the developed formulation is validated using full-scale test data of the ship KV Svalbard in Norway, testing the model as well as the numerical method. The effect of ice thickness, stem angle and breadth of bow on ship resistance is further investigated by means of the developed formulation.

Method of Virtual Power Applied to Cosserat Surfaces With Deformable Directors

1993 ◽  
Vol 46 (11S) ◽  
pp. S266-S278
Author(s):  
Boris Krajnc Alves ◽  
Jacob Lubliner
Keyword(s):  
Direct Method ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Momentum Balance ◽  
Power Method ◽  
Virtual Power ◽  
Balance Equations ◽  
Dimensional Theory ◽  
Momentum Balance Equation ◽  
Cosserat Surface

Following a brief outline of the method of virtual power, the local equations of motion for a Cosserat surface with inextensible directors are derived by means of this method. The model obtained coincides with the results derived from three-dimensional theory by Simo and Fox. Subsequently the model is extended so as to account for deformable directors. Besides the linear-momentum and moment-of-momentum balance equations, one additional scalar equation is derived. This equation replaces the director-momentum balance equation of Naghdi and therefore eliminates the necessity of introducing constitutive restrictions. The equivalence between the model derived by the virtual-power method and the results from the direct method of Naghdi are finally noted.

Dynamics of Inertia-Variant Flexible Systems Using Experimentally Identified Parameters

1986 ◽  
Vol 108 (3) ◽  
pp. 358-366 ◽  
Author(s):  
A. Shabana
Keyword(s):  
Differential Equations ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Analytical Techniques ◽  
Mode Shapes ◽  
Constraint Equations ◽  
Direct Numerical Integration ◽  
Parameter Estimation Techniques ◽  
Modal Coordinates ◽  
Algebraic Constraint

In this investigation modal parameters (frequency, damping, and mode shapes) which are determined experimentally using parameter estimation techniques are employed to simulate and predict the dynamic behavior of flexible multibody systems which consist of interconnected rigid and flexible components. The system differential equations of motion and algebraic constraint equations describing mechanical joints in the system are first identified using analytical techniques. Dynamic parameters such as mass, damping, and stiffness coefficients that appear in the system differential equations are then identified using a set of experimentally measured data. Mode shapes which are the result of the experimental identification are used to write the physical elastic coordinates of selected nodal points on the flexible body in terms of a reduced set of modal coordinates. The nonlinear differential and algebraic constraint equations are then written in terms of mixed sets of coupled reference and modal coordinates. These equations are integrated numerically using a direct numerical integration technique coupled with Newton–Raphson type iterations in order to check on constraint violations. The formulation developed is numerically exemplified using a three-dimensional dune buggy vehicle model.

Validation of a Belt Model for Prediction of Hub Forces from a Rolling Tire4

2009 ◽  
Vol 37 (2) ◽  
pp. 62-102 ◽  
Author(s):  
C. Lecomte ◽  
W. R. Graham ◽  
D. J. O’Boy
Keyword(s):  
Internal Pressure ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Prediction Method ◽  
Analytical Models ◽  
Beam Model ◽  
Impedance Boundary ◽  
Bending Waves ◽  
Tire Rotation ◽  
Three Dimensional Models

Abstract An integrated model is under development which will be able to predict the interior noise due to the vibrations of a rolling tire structurally transmitted to the hub of a vehicle. Here, the tire belt model used as part of this prediction method is first briefly presented and discussed, and it is then compared to other models available in the literature. This component will be linked to the tread blocks through normal and tangential forces and to the sidewalls through impedance boundary conditions. The tire belt is modeled as an orthotropic cylindrical ring of negligible thickness with rotational effects, internal pressure, and prestresses included. The associated equations of motion are derived by a variational approach and are investigated for both unforced and forced motions. The model supports extensional and bending waves, which are believed to be the important features to correctly predict the hub forces in the midfrequency (50–500 Hz) range of interest. The predicted waves and forced responses of a benchmark structure are compared to the predictions of several alternative analytical models: two three dimensional models that can support multiple isotropic layers, one of these models include curvature and the other one is flat; a one-dimensional beam model which does not consider axial variations; and several shell models. Finally, the effects of internal pressure, prestress, curvature, and tire rotation on free waves are discussed.

scholarly journals An Approach to Determine Optimal Bow Configuration of Polar Ships under Combined Ice and Calm-Water Conditions

2021 ◽  
Vol 9 (6) ◽  
pp. 680
Author(s):  
Hui Li ◽  
Yan Feng ◽  
Muk Chen Ong ◽  
Xin Zhao ◽  
Li Zhou
Keyword(s):  
Numerical Simulation ◽  
Water Resistance ◽  
Numerical Technique ◽  
Experimental Studies ◽  
Resistance Index ◽  
Simulation Method ◽  
Present Approach ◽  
Calm Water ◽  
Level Ice ◽  
Ice Resistance

Selecting an optimal bow configuration is critical to the preliminary design of polar ships. This paper proposes an approach to determine the optimal bow of polar ships based on present numerical simulation and available published experimental studies. Unlike conventional methods, the present approach integrates both ice resistance and calm-water resistance with the navigating time. A numerical simulation method of an icebreaking vessel going straight ahead in level ice is developed using SPH (smoothed particle hydrodynamics) numerical technique of LS-DYNA. The present numerical results for the ice resistance in level ice are in satisfactory agreement with the available published experimental data. The bow configurations with superior icebreaking capability are obtained by analyzing the sensitivities due to the buttock angle γ, the frame angle β and the waterline angle α. The calm-water resistance is calculated using FVM (finite volume method). Finally, an overall resistance index devised from the ship resistance in ice/water weighted by their corresponding weighted navigation time is proposed. The present approach can be used for evaluating the integrated resistance performance of the polar ships operating in both a water route and ice route.

scholarly journals Numerical methods for General Relativistic particles

2018 ◽  
Vol 14 (S342) ◽  
pp. 19-23
Author(s):  
Fabio Bacchini ◽  
Bart Ripperda ◽  
Alexander Y. Chen ◽  
Lorenzo Sironi
Keyword(s):  
Numerical Methods ◽  
Gravitational Lensing ◽  
Complex Dynamics ◽  
Equations Of Motion ◽  
Numerical Algorithms ◽  
Relativistic Effects ◽  
Compact Objects ◽  
Light Rays ◽  
Massive Particles ◽  
External Forces

AbstractWe present recent developments on numerical algorithms for computing photon and particle trajectories in the surrounding of compact objects. Strong gravity around neutron stars or black holes causes relativistic effects on the motion of massive particles and distorts light rays due to gravitational lensing. Efficient numerical methods are required for solving the equations of motion and compute i) the black hole shadow obtained by tracing light rays from the object to a distant observer, and ii) obtain information on the dynamics of the plasma at the microscopic scale. Here, we present generalized algorithms capable of simulating ensembles of photons or massive particles in any spacetime, with the option of including external forces. The coupling of these tools with GRMHD simulations is the key point for obtaining insight on the complex dynamics of accretion disks and jets and for comparing simulations with upcoming observational results from the Event Horizon Telescope.

Optimization of the Navy’s three-dimensional mine impact burial prediction simulation model, Impact35, using high-order numerical methods

2021 ◽  
pp. 154851292110286
Author(s):  
Athanasios Donas ◽  
Ioannis Famelis ◽  
Peter C Chu ◽  
George Galanis
Keyword(s):  
Numerical Analysis ◽  
Numerical Methods ◽  
Prediction Model ◽  
Simulation Model ◽  
Three Dimensional ◽  
Simulation System ◽  
High Order ◽  
Alternative Methodology ◽  
Runge Kutta ◽  
Fifth Order

The aim of this paper is to present an application of high-order numerical analysis methods to a simulation system that models the movement of a cylindrical-shaped object (mine, projectile, etc.) in a marine environment and in general in fluids with important applications in Naval operations. More specifically, an alternative methodology is proposed for the dynamics of the Navy’s three-dimensional mine impact burial prediction model, Impact35/vortex, based on the Dormand–Prince Runge–Kutta fifth-order and the singly diagonally implicit Runge–Kutta fifth-order methods. The main aim is to improve the time efficiency of the system, while keeping the deviation levels of the final results, derived from the standard and the proposed methodology, low.

scholarly journals Development and Validation of Quasi-Eulerian Mean Three-Dimensional Equations of Motion Using the Generalized Lagrangian Mean Method

2021 ◽  
Vol 9 (1) ◽  
pp. 76
Author(s):  
Duoc Nguyen ◽  
Niels Jacobsen ◽  
Dano Roelvink
Keyword(s):  
Surface Waves ◽  
Deep Water ◽  
Surf Zone ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Breaking Waves ◽  
Successful Implementation ◽  
Random Waves ◽  
Mean Motion ◽  
Generalized Lagrangian

This study aims at developing a new set of equations of mean motion in the presence of surface waves, which is practically applicable from deep water to the coastal zone, estuaries, and outflow areas. The generalized Lagrangian mean (GLM) method is employed to derive a set of quasi-Eulerian mean three-dimensional equations of motion, where effects of the waves are included through source terms. The obtained equations are expressed to the second-order of wave amplitude. Whereas the classical Eulerian-mean equations of motion are only applicable below the wave trough, the new equations are valid until the mean water surface even in the presence of finite-amplitude surface waves. A two-dimensional numerical model (2DV model) is developed to validate the new set of equations of motion. The 2DV model passes the test of steady monochromatic waves propagating over a slope without dissipation (adiabatic condition). This is a primary test for equations of mean motion with a known analytical solution. In addition to this, experimental data for the interaction between random waves and a mean current in both non-breaking and breaking waves are employed to validate the 2DV model. As shown by this successful implementation and validation, the implementation of these equations in any 3D model code is straightforward and may be expected to provide consistent results from deep water to the surf zone, under both weak and strong ambient currents.

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