A Procedure to Calculate First-Order Wave-Structure Interaction Loads in Wave Farms and Other Multi-Body Structures Subjected to Inhomogeneous Waves

A typical assumption when performing analytical, numerical, and experimental studies in wave–structure interaction in multi-body problems such as for wave farms and very large floating structures is the homogeneity of the wave field. Important interactions between the floating elements are dependent on the direction, amplitude, and phase of the waves acting on each. Then, wave homogeneity is probably unrealistic in near-shore areas where these installations are to be deployed. In the present work, an existing interaction method, which allows the use of standard boundary element diffraction codes for solving the first order wave structure linear potential for each unique geometry in the problem, is shown to be able to account for inhomogeneous sea states across the domain of a multi-body problem requiring only minimal modification to its implementation. A procedure to use the method to include arbitrary incoming undisturbed wave conditions at each body is presented. A verification study was done by using an artificial numerical configuration to mimic an inhomogeneous wave field in a standard diffraction code, which was used as a reference. The results obtained using the interaction-method based procedure are shown to be in excellent agreement with the reference ones. Furthermore, an example of frequency inhomogeneity of the wave field in a wave farm is shown and the effects on the motion amplitudes and absorbed power are presented illustrating the applicability of the procedure.

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Real-Time-Forecast of Wave-Structure Interaction in Natural Sea States: Influence of the Wave Encounter Angle

Volume 8B: Ocean Engineering ◽

10.1115/omae2014-24407 ◽

2014 ◽

Cited By ~ 1

Author(s):

Sascha Kosleck

Keyword(s):

Wave Field ◽

Transfer Functions ◽

Wave Structure ◽

Surface Elevation ◽

Just In Time ◽

Sea State ◽

Structure Interaction ◽

Model Scale ◽

Vessel Structure ◽

Wave Structure Interaction

In an offshore environment the ability to predict the development of a natural wave field can be of significant interest for a wide range of operations, such as for example on/off loading of cargo, installation or heavy lift processes, helicopter landing or even dynamic positioning. Being able to deterministically predict natural sea state just in time also allows for the prediction of wave structure interaction. Hence, not only motions in 6 degrees of freedom, for an arbitrary number of vessels or structures, but also velocities and accelerations at certain points of interest can be derived before they occur. Especially in difficult, slightly unclear weather conditions at the edge of operational limitations additional information on a potential exceedance of operational limits, such as for example wave heights, motions or accelerations, help to differentiate between safe and critical situations. Objective of the work conducted within the last years by Clauss, and Kosleck et al. is the development of a linear, deterministic approach for the just-in-time prediction of an ocean wave field of arbitrary specification. The survey presented within this paper focuses on the forecast of natural sea states and wave induced vessel/structure motions based on information gathered from a series of surface elevation snapshots of the surrounding free water surface. In order to investigate the approach a typical North Sea sea states with an underlying JONSWAP spectrum is generated and investigated at model scale. Simultaneous measurements of the surface elevation at over 450 different positions along the direction of wave propagation enable the artificial generation of surface elevation snapshots, used as input for the prediction method. Furthermore, these measurements also provide the basis for a comparison of calculated predictions and measurements at a huge variety of positions along the tank. The development of algorithms based on frequency domain analyses and the characterization of the sea state using a linear approach, enable the prediction of natural sea states in time and space — inside a well-defined range of validity. Knowing the general motion behaviour (transfer functions) of a structure/vessel together with the wave train to be encountered in the near future, its motion behaviour can subsequently be derived deterministically, taking into account that for the sailing vessel the transfer functions change depending on the actual cruising speed. The motion forecast procedure is compared and validated using measurements of the motion behaviour of an LNG carrier, again at model scale. So far, it has been shown (please see [1]) that the developed linear methods for the prediction of the motion behaviour of a stationary or cruising vessel/structure deliver excellent results for the vessel heading at different speeds but constant heading, namely 180° and 0° (defining head seas and following seas). This paper presents, for the first time, investigations with a vessel at zero speed but changing heading, hence a time varying change of the angle of wave attack.

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A Numerical Model Based on Navier-Stokes Equations to Simulate Water Wave Propagation with Wave-Structure Interaction

Wave Propagation Theories and Applications ◽

10.5772/51033 ◽

2013 ◽

Author(s):

Paulo Roberto de Freitas Teixeira

Keyword(s):

Wave Propagation ◽

Numerical Model ◽

Water Wave ◽

Stokes Equations ◽

Wave Structure ◽

Navier Stokes ◽

Navier Stokes Equations ◽

Structure Interaction ◽

Model Based ◽

Wave Structure Interaction

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Investigation of a Stochastic Inverse Method to Estimate an External Force: Applications to a Wave-Structure Interaction

Mathematical Problems in Engineering ◽

10.1155/2012/175036 ◽

2012 ◽

Vol 2012 ◽

pp. 1-25 ◽

Cited By ~ 3

Author(s):

S. L. Han ◽

Takeshi Kinoshita

Keyword(s):

External Force ◽

Inverse Method ◽

Inverse Function ◽

Wave Structure ◽

Dynamic Responses ◽

Structure Interaction ◽

External Forces ◽

Interaction Problem ◽

Wave Structure Interaction

The determination of an external force is a very important task for the purpose of control, monitoring, and analysis of damages on structural system. This paper studies a stochastic inverse method that can be used for determining external forces acting on a nonlinear vibrating system. For the purpose of estimation, a stochastic inverse function is formulated to link an unknown external force to an observable quantity. The external force is then estimated from measurements of dynamic responses through the formulated stochastic inverse model. The applicability of the proposed method was verified with numerical examples and laboratory tests concerning the wave-structure interaction problem. The results showed that the proposed method is reliable to estimate the external force acting on a nonlinear system.

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An overlapping domain decomposition based near-far field coupling method for wave structure interaction simulations

Coastal Engineering ◽

10.1016/j.coastaleng.2017.04.009 ◽

2017 ◽

Vol 126 ◽

pp. 37-50 ◽

Cited By ~ 6

Author(s):

Xin Lu ◽

Dominic Denver John Chandar ◽

Yu Chen ◽

Jing Lou

Keyword(s):

Domain Decomposition ◽

Wave Structure ◽

Coupling Method ◽

Far Field ◽

Structure Interaction ◽

Field Coupling ◽

Overlapping Domain Decomposition ◽

Wave Structure Interaction

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Efficient Solution of the 3D Laplace Problem for Nonlinear Wave-Structure Interaction

Volume 6: Nick Newman Symposium on Marine Hydrodynamics; Yoshida and Maeda Special Symposium on Ocean Space Utilization; Special Symposium on Offshore Renewable Energy ◽

10.1115/omae2008-57384 ◽

2008 ◽

Author(s):

Harry B. Bingham ◽

Allan P. Engsig-Karup

Keyword(s):

Nonlinear Wave ◽

Efficient Solution ◽

Wave Structure ◽

Finite Difference Schemes ◽

Surface Boundary ◽

Computational Domain ◽

Problem Size ◽

Structure Interaction ◽

Nonlinear Wave Structure ◽

Wave Structure Interaction

This contribution presents our recent progress on developing an efficient solution for fully nonlinear wave-structure interaction. The approach is to solve directly the three-dimensional (3D) potential flow problem. The time evolution of the wave field is captured by integrating the free-surface boundary conditions using a fourth-order Runge-Kutta scheme. A coordinate-transformation is employed to obtain a time-constant spatial computational domain which is discretized using arbitrary-order finite difference schemes on a grid with one stretching in each coordinate direction. The resultant linear system of equations is solved by the GMRES iterative method, preconditioned using a multigrid solution to the linearized, lowest-order version of the matrix. The computational effort and required memory use are shown to scale linearly with increasing problem size (total number of grid points). Preliminary examples of nonlinear wave interaction with variable bottom bathymetry and simple bottom mounted structures are given.

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