scholarly journals Time-domain, shallow-water hydroelastic analysis of VLFS elastically connected to the seabed

2016 ◽  
Vol 48 ◽  
pp. 33-51 ◽  
Author(s):  
A.E. Karperaki ◽  
K.A. Belibassakis ◽  
T.K. Papathanasiou
Keyword(s):  
Shallow Water ◽  
Time Domain ◽  
Hydroelastic Analysis

A Quasi-three-dimensional Finite-volume Shallow Water Model for Green Water on Deck

2013 ◽  
Vol 57 (03) ◽  
pp. 125-140
Author(s):  
Daniel A. Liut ◽  
Kenneth M. Weems ◽  
Tin-Guen Yen
Keyword(s):  
Shallow Water ◽  
Finite Volume ◽  
Time Domain ◽  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Three Dimensional ◽  
Green Water ◽  
Water Model ◽  
Ship Motions ◽  
Shallow Water Model

A quasi-three-dimensional hydrodynamic model is presented to simulate shallow water phenomena. The method is based on a finite-volume approach designed to solve shallow water equations in the time domain. The nonlinearities of the governing equations are considered. The methodology can be used to compute green water effects on a variety of platforms with six-degrees-of-freedom motions. Different boundary and initial conditions can be applied for multiple types of moving platforms, like a ship's deck, tanks, etc. Comparisons with experimental data are discussed. The shallow water model has been integrated with the Large Amplitude Motions Program to compute the effects of green water flow over decks within a time-domain simulation of ship motions in waves. Results associated to this implementation are presented.

Time Domain Hydroelastic Analysis of a Flexible Marine Structure Using State-Space Models

2007 ◽  
Author(s):  
Reza Taghipour ◽  
Tristan Perez ◽  
Torgeir Moan
Keyword(s):  
Mathematical Model ◽  
State Space ◽  
Time Domain ◽  
State Space Model ◽  
Realization Theory ◽  
Regular Waves ◽  
Alternative State ◽  
Marine Structure ◽  
Hydroelastic Analysis ◽  
The Mathematical Model

This article deals with time-domain hydroelastic analysis of a marine structure. The convolution terms in the mathematical model are replaced by their alternative state-space representations whose parameters are obtained by using the realization theory. The mathematical model is validated by comparison to experimental results of a very flexible barge. Two types of time-domain simulations are performed: dynamic response of the initially inert structure to incident regular waves and transient response of the structure after it is released from a displaced condition in still water. The accuracy and the efficiency of the simulations based on the state-space model representations are compared to those that integrate the convolutions.

Time-Domain Hydroelastic Analysis of a Flexible Marine Structure Using State-Space Models

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
Reza Taghipour ◽  
Tristan Perez ◽  
Torgeir Moan
Keyword(s):  
State Space ◽  
Time Domain ◽  
State Space Model ◽  
Space Representation ◽  
Regular Waves ◽  
State Space Representation ◽  
Alternative State ◽  
Marine Structure ◽  
Hydroelastic Analysis ◽  
The Mathematical Model

This article deals with time-domain hydroelastic analysis of a marine structure. The convolution terms associated with fluid memory effects are replaced by an alternative state-space representation, the parameters of which are obtained by using realization theory. The mathematical model established is validated by comparison to experimental results of a very flexible barge. Two types of time-domain simulations are performed: dynamic response of the initially inert structure to incident regular waves and transient response of the structure after it is released from a displaced condition in still water. The accuracy and the efficiency of the simulations based on the state-space model representations are compared to those that integrate the convolutions.

scholarly journals Application of contact elements to represent prismatic mechanical couplings

2019 ◽  
Vol 272 ◽  
pp. 01028
Author(s):  
Mahdi Ghesmi ◽  
Bettar Ould el Moctar
Keyword(s):  
Numerical Simulations ◽  
Shallow Water ◽  
Time Domain ◽  
Element Model ◽  
Contact Element ◽  
Suitable Method ◽  
Regular Waves ◽  
Mechanical Coupling ◽  
Prismatic Joints ◽  
Coupled Structures

Accurate prediction of loads on mechanical couplings is crucial in assessment of loads on coupled structures and in optimization of mechanical coupling design. In this paper, a contact element model is introduced to represent prismatic joints. A twofold pushing convoy in shallow water was taken for time domain numerical simulations in regular waves. The prismatic joints interconnecting the convoy bodies allowed relative heave and pitch motions of the bodies relative to each other. The articulation forces and body motions were compared to model basin measurements to assess the reliability of contact element model. The contact element model could simulate the prismatic joints efficiently and it provided a suitable method to idealize free and suppressed modes at articulation locations.

Mating Analysis and a Typical Floatover Design

2012 ◽  
Author(s):  
Alan M. Wang ◽  
Ruhua Yuan ◽  
Shaohua Zhu ◽  
Min He ◽  
Ju Fan ◽  
...  
Keyword(s):  
Diffraction Analysis ◽  
Shallow Water ◽  
Frequency Domain ◽  
Time Domain ◽  
Bohai Bay ◽  
Hydrodynamic Properties ◽  
Nonlinear Time Domain ◽  
Offshore Operations

This paper presents a typical floatover design in the shallow water and benign environment of Bohai Bay, China and the major floatover installation devices, as well as the nonlinear time-domain mating analysis. The nonlinear mating simulations are performed using SIMO based on the hydrodynamic properties of the floatover barge, obtained by WADAM, from the linear diffraction analysis in frequency domain. The mating analysis yields numerical findings in selecting and designing floatover devices critical to the success of the floatover operations, thus minimizing any potential operation risks and enabling the offshore operations as smoothly and efficiently as possible.

Integrated Analysis of Mooring and Riser Systems for FPSO’s in Harsh Shallow Water Environments

2011 ◽  
Author(s):  
M. Martens ◽  
J. R. Whelan ◽  
Y. Drobyshevski
Keyword(s):  
Shallow Water ◽  
Time Domain ◽  
Integrated Approach ◽  
Integrated Analysis ◽  
Mooring System ◽  
South East Asia ◽  
Riser Design ◽  
Design Case ◽  
East Asia Region ◽  
Design Challenges

Shallow water mooring and riser systems for permanently turret moored FPSOs present significant design challenges. Many FPSOs, in particular in the South-East Asia region, are required to remain on-station in 100-year return period tropical revolving storm (typhoon) conditions. Extreme sea states combined with the restricted height of the water column generate large mooring loads and make it difficult to accommodate conventional riser configurations. Metocean conditions in such areas can be highly directional. This directionality can be exploited by undertaking an integrated mooring and riser design analysis. The critical interface between the mooring and riser systems is the turret offset and the associated turret heave. The conventional approach is to identify a single offset envelope for each design case, comprising the mooring system (intact or damaged) and FPSO condition (loaded or ballasted), which is then used in riser design. This paper presents a more developed approach, the integrated approach, which is based on conducting the mooring and riser analyses simultaneously for a common set of design cases. To exploit the directionality of the metocean conditions, an offset envelope for each governing metocean condition is calculated from time domain mooring simulations, followed by a parameterisation scheme. As a result, multiple turret offsets and associated metocean conditions and FPSO headings are identified which form a family of offsets for each compass octant of the environment. The integrated approach is applied to an example FPSO with an external turret supporting seven risers arranged in double wave tethered configuration. The drivers and advantages for selecting a particular riser configuration are discussed. It is shown how application of an integrated analysis approach leads to less conservative combinations for use in the riser design, and enables the development of a feasible riser system. An optimal mooring pattern, both leg make-up and orientation for riser layout, is also developed.

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