A Roll Damping Analysis of a Standard US Naval Hull Form (DTMB 5415)

2021 ◽  
Vol 163 (A1) ◽  
pp. 79-86
Author(s):  
L F Hu ◽  
Q T Gong ◽  
Z M Yuan ◽  
X Y Wang ◽  
J X Duan
Keyword(s):  
Numerical Simulation ◽  
Vof Method ◽  
Navier Stokes ◽  
Roll Motion ◽  
Ship Motions ◽  
Stability Criteria ◽  
Fluid Interface ◽  
Roll Damping ◽  
Hull Form ◽  
Us Navy

Accurate prediction of roll damping is important in calculating the roll motion of a ship. This paper presents a roll decay analysis of an intact US Navy Destroyer hull form (DTMB 5415) using a Navier–Stokes (NS) solver with the volume of fluid (VOF) method. Dynamic overset mesh techniques were employed to handle mesh updating required to obtain transient ship motions. The VOF method was used to capture the fluid interface. The effect of turbulence was considered by means of a k-w and a k-e model. A sensitivity analysis was conducted, in terms of the grid, timesteps and degree of freedom. The roll decay results of the numerical simulation have been compared with those of prior physical model testing (Gokce and Kinaci, 2018), and the different roll decay responses used to predict the roll damping. It is intended that this research be a useful step towards establishing intact ship stability criteria, as part of current research.

Time-Domain Flooding Simulation of a Damaged Warship

2020 ◽  
Vol 54 (2) ◽  
pp. 69-78
Author(s):  
Li-fen Hu ◽  
Hao Wu ◽  
Qingtao Gong ◽  
Xiangyang Wang ◽  
Wenbin Lv
Keyword(s):  
Experimental Data ◽  
Time Domain ◽  
Stability Criterion ◽  
Vof Method ◽  
Navier Stokes ◽  
Ship Motions ◽  
Fluid Interface ◽  
Complex Dynamic ◽  
Turbulence Effect ◽  
Mesh Update

AbstractUnderstanding of the complex dynamic behavior of damaged ships and floodwater remains limited for ship designers and safety authorities. In this work, a Navier-Stokes (NS) solver that combines the volume of fluid (VOF) method with overset mesh techniques is developed to simulate the flooding process of a damaged ship. The VOF method captures the fluid interface, and the turbulence effect on flows is considered with the k-ω model. The overset mesh techniques are employed to handle the mesh update following transient ship motions. Then, the results of a damaged barge with dynamic and overset mesh are compared with the experimental data. On the basis of this validation, the solver is applied to the flooding problems of a damaged warship. This research is intended to be a useful step toward the establishment of a stability criterion for damaged ships in the future.

Numerical Simulation of Roll Damping

2006 ◽  
Author(s):  
Juan B. V. Wanderley ◽  
Andre´ Ramiro ◽  
Thiago Reis ◽  
Antonio Carlos Fernandes ◽  
Carlos Levi
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Vortex Formation ◽  
Integral Form ◽  
Quantitative Agreement ◽  
Navier Stokes ◽  
Roll Damping ◽  
Navier Stokes Equations ◽  
Decay Tests ◽  
Volume Method

The highly viscous flow problem of roll damping of a FPSO is investigated by means of numerical solution of the unsteady two-dimensional Navier-Stokes equations. The finite volume method using non-structured grid is used to solve the integral form of the governing equations. The cross section of the FPSO hull with an initial roll displacement is let free to oscillate in roll in an initially still fluid. The numerical simulation provides a realistic picture of the physics of the phenomenon, capturing the vortex formation around the bilge keel. Numerical results from roll free decay tests are compared with experimental data showing a fairly good qualitative and quantitative agreement of the roll damping.

Roll Damping Simulations of an Offshore Heavy Lift DP3 Installation Vessel Using the CFD Toolbox OpenFOAM

2020 ◽  
Author(s):  
Brecht Devolder ◽  
Florian Stempinski ◽  
Arjan Mol ◽  
Pieter Rauwoens
Keyword(s):  
Boundary Element ◽  
Damping Coefficient ◽  
Navier Stokes ◽  
Roll Motion ◽  
Viscous Effects ◽  
Roll Damping ◽  
Two Phase ◽  
Damping Behavior ◽  
External Moment ◽  
Heavy Lift

Abstract In this work, the roll damping behavior of the offshore heavy lift DP3 installation vessel Orion from the DEME group is studied. Boundary element codes using potential flow theory require a roll damping coefficient to account for viscous effects. In this work, the roll damping coefficient is calculated using the Computational Fluid Dynamics (CFD) toolbox OpenFOAM. The two-phase Navier-Stokes fluid solver is coupled with a motion solver using a partitioned fluid-structure interaction algorithm. The roll damping is assessed by the Harmonic Excited Roll Motion (HERM) technique. An oscillating external moment is applied on the hull and the roll motion is tracked. Various amplitudes and frequencies of the external moment and different forward speeds, are numerically simulated. These high-fidelity full-scale simulations result in better estimations of roll damping coefficients for various conditions in order to enhance the accuracy of efficient boundary element codes for wave-current-structure interactions simulations.

Numerical Simulation of Ship Motions in Regular and Irregular Waves

2019 ◽  
Vol 53 (1) ◽  
pp. 97-106
Author(s):  
Bao-Ji Zhang ◽  
Jie Liu ◽  
Ning Xu ◽  
Lei Niu ◽  
Wen-Xuan She
Keyword(s):  
Numerical Simulation ◽  
Wave Length ◽  
Simulation Method ◽  
Irregular Waves ◽  
Navier Stokes ◽  
Ship Motions ◽  
Vof Model ◽  
Split Operator ◽  
Strip Theory ◽  
Cfd Method

AbstractA numerical simulation method is presented in this study to predict ship resistance and motion responses in regular and irregular waves. The unsteady RANS (Reynolds Average Navier-Stokes) method is selected as the governing equation, and a volume of fluid (VoF) model is used to capture the free surface, combining the k-ε equations. A finite volume method (FVM) is utilized to discretize both the RANS equations and VoF transport equation. The pressure implicit split operator (PISO) method is set as the velocity-pressure coupling equation. The overset mesh technique is utilized to simulate ship motions in waves. A DTMB5415 ship is selected as a case study to predict its pitch and heave responses in regular and irregular waves at different wave length and wave steepness. The ship is free to move in the pitch and heave directions. The CFD (Computational Fluid Dynamics) results are found to be in good agreement with the strip theory and experimental data. It can be found that the CFD method presented in this study can provide a theoretical basis and technical support for green design and manufacture of ships.

Hydrodynamic Performance and Appendage Considerations of Wave-Piercing Planing Craft Overlapping Waves and Porpoising

2019 ◽  
Author(s):  
Sang-Won Kim ◽  
Sang-Eui Lee ◽  
Gyoung-Woo Lee ◽  
Kwang-Cheol Seo ◽  
Nobuyuki Oshima
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
High Speed ◽  
Numerical Study ◽  
Hydrodynamic Performance ◽  
Moving Mesh ◽  
Navier Stokes ◽  
Hull Form ◽  
Wave Condition ◽  
Planing Craft

Abstract This work addresses the numerical study of wave-piercing planing hull and related hydrodynamic performance as the appendages. From the half century ago, the interest in high-speed planing crafts has been advanced toward maintaining performance stably. The main reasons to make it hard are instability motion occurring from porpoising and wave condition. Porpoising is mainly due to overlap the heaving and pitching motion with certain period, which is caused by instable pressure distribution and changing longitudinal location of center of gravity. In addition, in wave condition, encountering wave disturbs going into planing mode. This paper presents numerical results of wave-piercing planing hull in porpoising and wave condition. Numerical simulation is conducted via Reynolds Averaged Navier-stokes (RANS) with moving mesh techniques (overset grid), performed at different wave condition. The results for the behaviors of wave-piercing hull form are practically presented and investigated in this study. The understanding of these phenomena is important for design of appendages of wave-piercing hull-form.

Numerical Simulation of Roll Damping of a FPSO

2007 ◽  
Author(s):  
Juan B. V. Wanderley ◽  
Andre´ Ramiro ◽  
Thiago Reis ◽  
Antonio Carlos Fernandes ◽  
Carlos Levi
Keyword(s):  
Numerical Simulation ◽  
Stokes Equations ◽  
Vortex Formation ◽  
Integral Form ◽  
Quantitative Agreement ◽  
Navier Stokes ◽  
Roll Damping ◽  
Navier Stokes Equations ◽  
Volume Method ◽  
Bilge Keel

The viscous flow problem of roll damping of a FPSO is investigated by means of numerical solution of the unsteady two-dimensional Navier-Stokes equations. The finite volume method using unstructured grid is used to solve the integral form of the governing equations. The cross section of the FPSO hull with an initial roll displacement is left free to oscillate in roll, heave and sway in an initially still fluid. The numerical simulation provides a realistic picture of the physics of the phenomenon, capturing the vortex formation around the bilge keel. The numerical results are compared with experimental data showing a fairly good qualitative and quantitative agreement of the motion damping.

scholarly journals The CFD Method-Based Research on Damaged Ship’s Flooding Process in Time-Domain

2019 ◽  
Vol 26 (1) ◽  
pp. 72-81
Author(s):  
Hu Li-Fen ◽  
Qi Huibo ◽  
Li Yuemeng ◽  
Li Wubin ◽  
Chen Shude
Keyword(s):  
Time Domain ◽  
Vof Method ◽  
Dynamic Mesh ◽  
Navier Stokes ◽  
Ship Motions ◽  
Starting Point ◽  
Cfd Method ◽  
The Time Domain ◽  
Dead Ship Condition ◽  
Damaged Ship

Abstract The flooding process is one of the main concerns of damaged ship stability. This paper combines the volume of fluid (VOF) method incorporated in the Navier-Stokes (NS) solver with dynamic mesh techniques to simulate the flooding of a damaged ship. The VOF method is used to capture the fluid interface, while the dynamic mesh techniques are applied to update the mesh as a result of transient ship motions. The time-domain flooding processes of a damaged barge and a rectangular cabin model are carried out based on the abovementioned method, and the computational results appear compatible with the experimental data. During the flooding process, the motion of the flooding flow at different stages is observed and compared with that observed in real conditions. The time-domain research of the flooding process is the starting point for subsequent establishment of damaged ship’s roll movement and capsizing the mechanism of dead ship condition in wave.

Modelling of Roll Damping Effects for a Fishing Vessel With Forward Speed

2015 ◽  
Author(s):  
K. G. Aarsæther ◽  
D. Kristiansen ◽  
B. Su ◽  
C. Lugni
Keyword(s):  
Large Amplitude ◽  
Well Being ◽  
Roll Motion ◽  
Ship Motions ◽  
Limiting Factor ◽  
Real Problem ◽  
Forward Speed ◽  
Roll Damping ◽  
Damping Effects ◽  
Wave Induced

Vessels in the ocean-going fishing fleet are in general operating in almost all weather conditions. This includes operation in high sea-states which may lead to large amplitude ship motions, depending on the seakeeping characteristics of the vessel. Wave-induced ship motions are important factors for the safety and well-being of fishermen at work. Generally, potential flow theory overpredicts wave-induced roll motion amplitudes for conventional ship hulls. This is due to the presence of viscous damping effects in reality. Large amplitude roll motion of ships can be a real problem if no anti-rolling devices (e.g. bilge keels, anti-rolling tanks or roll-damping fins) are installed, as the roll damping coefficient of a ship is the limiting factor for the resonant roll motion amplitudes. The different components of roll damping for a ship at forward speed were investigated by Ikeda et al. [1], [2] and [3] and updated guidelines for numerical estimation of roll damping have been presented by the International Towing Tank Conference [4], where a component discrete type method for estimation of the damping is suggested. The different roll-damping components of Ikeda et al. has been complemented by skeg damping for smooth hulls [5]. This paper presents comparison between model experiments and the numerical results obtained from the guidelines [4] where the effects of bilge-keels and skeg are isolated.

A RANS Based Method for the Estimation of Ship Roll Damping With Forward Speed

2004 ◽  
Author(s):  
Kumar B. Salui ◽  
Vladimir Shigunov ◽  
Dracos Vassalos
Keyword(s):  
High Speed ◽  
Turbulence Modeling ◽  
Finite Difference Methods ◽  
Computer Hardware ◽  
Navier Stokes ◽  
Roll Motion ◽  
Ship Motions ◽  
Viscous Effects ◽  
Flow Models ◽  
Ship Roll

For the prediction of ship roll motion, viscous effects must be taken into account. Several methods, experimental and theoretical, have previously been used to calculate hydrodynamic forces in roll motion. Theoretical methods applied so far to this problem have been based mainly on potential flow models, which cannot account for viscous effects adequately or need pre-defined flow separation like vortex methods. Recent development of computer hardware enables application of methods based on flow field discretisation such as finite-difference methods to solution of problems of practical ship design such as ship motions and control. In the present study, a Reynolds-Averaged Navier-Stokes solver is used to calculate hydrodynamic loads during forced roll motion at different Froude numbers. The solution method adopted is based on unstructured finite-volume discretisation with collocated arrangement of flow variables. A pressure-correction algorithm (SIMPLE) is used for the pressure-velocity coupling. A standard k–ε model is used for the turbulence modeling. An advanced differencing scheme called high-resolution interface capturing (HRIC) is used for accurate resolution of the free surface in the scope of a multiphase-type description. A high-speed hard chine vessel with and without skeg is studied. Close agreement is found between the present calculations and experimental results.

Experimental Investigation of Viscous Roll Damping on the DTMB Model 5617 Hull Form

2007 ◽  
Author(s):  
Paisan Atsavapranee ◽  
Jason B. Carneal ◽  
David Grant ◽  
A. Scott Percival
Keyword(s):  
Flow Field ◽  
Lateral Force ◽  
Added Mass ◽  
Viscous Drag ◽  
Experimental Investigations ◽  
Roll Motion ◽  
Forward Speed ◽  
Roll Damping ◽  
Hull Form ◽  
Bilge Keel

A systematic series of model tests have been performed at NSWCCD to explore the mechanisms of roll damping around a conventional combatant hull form (DTMB model #5617) and an advanced tumble-home hull form (DTMB model #5613-1). Both free roll decay and forced oscillation experiments were carried out in calm water and in waves, over a range of forward speeds. These experimental investigations were performed within the overall context of continuing efforts to advance the capability to assess seakeeping, maneuvering, and dynamic stability characteristics of a surface combatant. Data gathered in these experiments are currently being utilized to develop empirical and analytical roll damping models and to validate the accuracy of simulation programs in the calculation of various components of hydrodynamic forces. This paper will specifically discuss a single-degree-of-freedom free roll decay experiment, with measurements of the appendage lateral force and the associated flow field generated during ship roll motion on the DTMB #5617 model. Using particle-image velocimetry (PIV) measurements, two-dimensional unsteady flow patterns around the bilge keels were performed to study the mechanisms of viscous roll damping due to bilge keels. In addition, lateral forces and moments on the bilge keels, rudders, and propellers have been measured to provide a direct assessment of component roll damping. Analysis for appendage forces and correlation with the measured flow field yield several new important insights into the physical mechanisms of bilge keel roll damping. Flow field observation reveals complex phenomena of viscous flow separations and vortex formation around the bilge keel during different phases of the roll motion cycle. The lateral force on the bilge keels was modeled as the sum of an added mass component and a viscous drag component. The viscous drag coefficients are found to depend strongly on ship forward speed and roll amplitude, but the added mass coefficients are relatively constant for the range of forward speed and roll amplitude investigated.

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