A Parametric Study of Wave - Structure Interaction Using the Coupled Transient CFD and Diffraction Methodology

2014 ◽  
Author(s):  
David Jia ◽  
Madhusuden Agrawal ◽  
Jim Malachowski
Keyword(s):  
Steady State ◽  
Diffraction Analysis ◽  
Time Domain ◽  
Cfd Simulation ◽  
Wave Structure ◽  
Structure Interaction ◽  
Added Masses ◽  
Parametric Studies ◽  
Traditional Approaches ◽  
Wave Structure Interaction

This paper is a continuation of our previous paper [1] (OMAE2013-11569) where we demonstrated a state-of-the-art methodology for predicting the motions and loads of subsea equipment and structures during offshore operations basing on time domain simulations of subsea equipment and structures. Instead of relying on simplified equations or empirical formulations to calculate and estimate the hydrodynamics coefficients, or using steady-state CFD simulation on a stationary equipment and structure to predict drag and added masses on submerged structures in traditional approaches, this methodology couples the transient CFD with diffraction analysis. The time domain diffraction simulation is coupled with multiphase CFD simulation of subsea equipment and structures in waves. Transient CFD model with rigid body motion for the equipment and structure calculates added masses, forces and moments on the equipment and structure for diffraction analysis, while diffraction analysis calculates linear and angular velocities for CFD simulation. In this paper, parametric studies are performed to investigate effect of wavelength, wave amplitude and wave current on the motion of a hollow cylinder in waves. The results of the parametric studies in this paper show wave-structure interaction of a hollow cylinder in waves, and the effect of waves and current on the motion of the cylinder and the associated forces. The results provide better understanding of structure motion and associated forces in waves using this coupled methodology. The coupled methodology eliminates the inaccuracy inherited from assumed or calculated hydrodynamic properties that are obtained by using simplified equations or empirical formulations [2], or by using steady-state CFD analyses in traditional decoupled approaches. The results show that the coupled physics of wave and cylinder motion is captured by using this methodology, otherwise is not captured by traditional approaches. This coupled methodology has potential applications in analyses of the motions of subsea equipment and structures in wave during offshore operations.

Modelling of Wave-Structure Interaction of a Cylinder in Regular Sea Waves With Vessel Motions Using Coupled Transient CFD and Diffraction Methodology

2015 ◽  
Author(s):  
David Jia ◽  
Paul Schofield ◽  
Joanne Shen ◽  
Jim Malachowski
Keyword(s):  
Steady State ◽  
Hollow Cylinder ◽  
Cfd Simulation ◽  
Traditional Approach ◽  
Wave Structure ◽  
Sea Waves ◽  
Regular Waves ◽  
Structure Interaction ◽  
Added Masses ◽  
Wave Structure Interaction

This paper is a continuation of our previous paper [1] (OMAE2014-23225) where we did a parametric study for wave-structure interaction of a hollow cylinder in regular sea waves without vessel motions. The effect of waves and current on the motion of the cylinder and the associated forces were evaluated using a state-of-the-art methodology [2] (OMAE2013-11569) for predicting the motions and loads of subsea equipment and structures during offshore operations. In this paper, we extend the solution to include wave – structure interaction in regular sea waves and vessel motions. The 5th order Stokes regular waves in CFD and vessel motions are included in the modeling. This methodology couples the transient CFD with a hydrodynamic motion analysis after diffraction analyses, instead of relying on the traditional approach which uses simplified equations or empirical formulae to estimate hydrodynamic coefficients [3], or using steady-state CFD simulation on stationary equipment and structures to predict drag and added masses on submerged structures. The time domain diffraction simulation is coupled with a multiphase CFD simulation of subsea equipment and structures in waves. A transient CFD model with rigid body motions for the equipment and structures calculates added masses, forces and moments on the equipment and structures for the diffraction analysis, while the diffraction analysis calculates linear and angular velocities for the CFD simulation. In this paper, simulations are performed to investigate effect of the vessel motions on the motion of a hollow cylinder in regular sea waves. The results are compared with that from the traditional approach. This coupled methodology has potential applications in analyses of the motions of subsea equipment and structures in waves during offshore operations. The results in this paper show wave-structure interaction of a hollow cylinder in regular sea waves, and the effect of vessel motions on the motion of the cylinder. The results provide better understanding of structure motion in regular waves with vessel motions using this coupled methodology. The coupled methodology eliminates the inaccuracy inherited from assumed or calculated hydrodynamic properties that are obtained by using simplified equations or empirical formulations, or by using steady-state CFD analyses in traditional decoupled approaches. The results show that the coupled physics of regular sea waves, vessel motions and cylinder motion is captured by using this methodology. The coupled physics is not captured by the traditional approach.

Coupled Transient CFD and Diffraction Modeling for Installation of Subsea Equipment/Structures in Splash Zone

2013 ◽  
Author(s):  
David Jia ◽  
Madhusuden Agrawal
Keyword(s):  
Steady State ◽  
Diffraction Analysis ◽  
Time Domain ◽  
Cfd Simulation ◽  
Load Level ◽  
Body Motion ◽  
Splash Zone ◽  
Wave Loads ◽  
Added Masses ◽  
Hydrodynamics Coefficients

In development of deep water oil and gas fields, successfully and economically installing subsea equipment and structure is critically important. This paper presents a state-of-the-art methodology for predicting the motions and loads of subsea equipment/structure during such operations basing on time domain simulations of the combined installation vessel and subsea equipment/structure. The time domain diffraction simulation of the moving lifting vessel is coupled with multiphase CFD simulation of subsea equipment/structure in splash zone. Transient CFD model with rigid body motion for the equipment/structure calculates added masses, forces and moments on the equipment/structure for diffraction analysis, while diffraction analysis calculates linear and angular velocities for CFD simulation. This paper has many potential applications, such as, installation of pile, manifold, subsea tree, PLET/PLEM, or other subsea equipment/structure. This coupled approach has been successfully implemented on a cylindrical structure. The results show that total load level, and dynamics of the subsea equipment/structure due to waves in splash zone are predicted. Current practice of installation analysis in accordance with the recommendations from DNV-RP-H103 [1] cannot determine in detail the wave loads either during the passage through splash zone, or added mass and damping when the equipment/structure is submerged. In order to determine wave loads in detail, model tests are needed. In the absence of tests, simplified equations or empirical formulations have to be used to calculate/estimate these hydrodynamics coefficients as recommended in DNV-RP-H103. Steady-state CFD simulations on a stationary equipment/structure are usually used to predict drag and added masses on submerged structures. However the steady-state assumption in CFD ignores the resonating motion of equipment/structure in calculating hydrodynamics coefficients, which can severely affect the accuracy of these predictions. The above methods often give overly conservative results for allowable sea state which results in uneconomical vessel time or inaccurate results for installation. The methodology of this paper gives more accurate results, and provides potentially economical vessel time during installation. The intent of this paper is to demonstrate the solution and methodology.

scholarly journals Time-Dependent Wave-Structure Interaction Revisited: Thermo-Piezoelectric Scatterers

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 101
Author(s):  
George C. Hsiao ◽  
Tonatiuh Sánchez-Vizuet
Keyword(s):  
Field Equation ◽  
Time Domain ◽  
Wave Structure ◽  
Scaling Factor ◽  
Time Dependent ◽  
Laplace Domain ◽  
Boundary Field ◽  
Structure Interaction ◽  
The Time Domain ◽  
Wave Structure Interaction

In this paper, we are concerned with a time-dependent transmission problem for a thermo-piezoelectric elastic body that is immersed in a compressible fluid. It is shown that the problem can be treated by the boundary-field equation method, provided that an appropriate scaling factor is employed. As usual, based on estimates for solutions in the Laplace-transformed domain, we may obtain properties of corresponding solutions in the time-domain without having to perform the inversion of the Laplace-domain solutions.

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

2012 ◽  
Vol 2012 ◽  
pp. 1-25 ◽  
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.

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

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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