Citation for published version (APA): Kleefsman, K. M. T. (2005). Water impact loading on offshore structures. - A numerical study s.n.

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1 University of Groningen Water impact loading on offshore structures. - A numerical study Kleefsman, Kornelia Marchien Theresa IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2005 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Kleefsman, K. M. T. (2005). Water impact loading on offshore structures. - A numerical study s.n. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date:

2 Water Impact Loading on Offshore Structures A Numerical Study Theresa Kleefsman

3 The research presented in this thesis was funded by the European Community under the Competitive and Sustainable Growth Programme (EU Project No.: GRD ) and a group of 26 industrial participants (oil companies, shipyards, engineering companies, regulating bodies) as part of the SafeFLOW JIP, coordinated by MARIN. The author is solely responsible for the present thesis and it does not represent the opinion of the European Community. On the cover: Storm on the sea of Galilee, Rembrandt, 1633 And behold there arose a great storm on the sea, so that the boat was being swamped by the waves..., Matthew 8.24

4 Rijksuniversiteit Groningen Water Impact Loading on Offshore Structures A Numerical Study Proefschrift ter verkrijging van het doctoraat in de Wiskunde en Natuurwetenschappen aan de Rijksuniversiteit Groningen op gezag van de Rector Magnificus, dr. F. Zwarts, in het openbaar te verdedigen op vrijdag 18 november 2005 om uur door Kornelia Marchien Theresa Kleefsman geboren op 18 maart 1977 te Veendam

5 Promotor: Beoordelingscommissie: Prof. dr. A.E.P. Veldman Prof. N. Barltrop Prof. dr. ir. B. Koren Prof. dr. ir. J.A. Pinkster ISBN X

6 Contents 1 Introduction Problem definition Focus on green water events Description of the simulation method Grid and discretisation Free surface displacement Moving objects Generation and propagation of waves Generation of waves using wave description theory Wave field calculation by an external program Wave generation for validation using an experiment Wave propagation Outline Fluid Flow in a Closed Domain Introduction Mathematical Model Governing Equations Boundary Conditions Discretisation of the governing equations Grid and geometry definition Motion of a rigid object Cell labelling Discretisation of the continuity equation Spatial discretisation of the Navier-Stokes equations Temporal discretisation and solution method Stability Solid wall boundary conditions Pressure at the free surface Velocities at the free surface: SE-velocities Velocities at the free surface: EE-velocities Free surface displacement Overview of VOF methods Hirt-Nichols VOF Local height function Youngs VOF

7 vi Contents Test of simple translation Rotation of a slotted disk Rotation of a three-dimensional notched brick Single vortex Two-dimensional dambreak simulation Concluding remarks Free surface displacement and moving objects Pressure spikes due to moving objects Validation: flow of a breaking dam Validation: water entry Wedge entry Cone entry Entry of a circular cylinder Wave generation and propagation Introduction Wave definition Airy wave theory Wave kinematics above the calm water level th order Stokes theory Treatment of open boundaries Overview outflow boundary conditions Non-reflecting boundary conditions Dissipation zone: pressure damping at the free surface Free surface velocities Wave propagation using different VOF methods Validation of wave propagation Two-dimensional wave propagation: regular waves Two-dimensional wave propagation: steep wave events Regular wave loading on a spar platform Green water on the deck of a moving FPSO Generation of waves using zonal modelling Introduction Description of the zonal modelling method Simulation of an irregular wave Wave loading on a spar platform Simulation of green water loading Simulation using zonal modelling Comparison with simulation initialised using experimental data Grid refinement Discussion of the results Conclusions and recommendations 129 Bibliography 135

8 Contents vii Samenvatting 143 Dankwoord 151

Water Impact Loading on Offshore Structures

Water Impact Loading on Offshore Structures A Numerical Study Theresa Kleefsman The research presented in this thesis was funded by the European Community under the Competitive and Sustainable Growth Programme