20 YEARS OF RESEARCH IN HYDRODYNAMIC AND STRUCTURE AT BUREAU VERITAS

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1 ATMA YEARS OF RESEARCH IN HYDRODYNAMIC AND STRUCTURE AT BUREAU VERITAS Quentin DERBANNE, Sime MALENICA, Xiao-Bo CHEN, Louis DIEBOLD BUREAU VERITAS Division Marine & Offshore Neuilly-sur-Seine RESUME Les travaux du Département Recherche du Bureau Veritas ont été récompensés par le prix 2013 du CEMT (Confederation of European Maritime Technology Societies). A cette occasion, ce mémoire revient sur les innovations principales de ces 20 dernières années dans les domaines de l hydrodynamique et de l hydro-structure. Les logiciels HydroStar et Homer, développés par Bureau Veritas, ont bénéficié de nombreuses innovations et sont maintenant des références dans leur domaine largement utilisés de par le monde. Dans le domaine du sloshing, Bureau Veritas a su développer une expertise de haut niveau grâce à des essais sur maquette indépendants, à l emploi de la CFD et à des travaux sur les statistiques des pressions de sloshing. Enfin des travaux importants ont été menés sur les méthodologies de design, permettant de faire le lien entre l approche calcul direct et l approche réglementaire. SUMMARY The Confederation of European Maritime Technology Societies (CEMT) 2013 Award in recognition of a significant contribution to the European Maritime Industry was made to the Research Department of the Marine Division of Bureau Veritas for their outstanding research in the field of hydrodynamics and hydro-structure. This paper gives a quick overview of the past 20 years of innovations in these fields. HydroStar and Homer software, developed by Bureau Veritas, are based on many innovations, and are now at the state of the art level and widely used worldwide. Bureau Veritas has developed a very high level expertise in sloshing, based on independent sloshing model tests, the use of CFD and research on statistical laws to extrapolate the sloshing pressures. Finally important work has been done on design methodologies that enables to treat the direct computation approach and the rule approach in a consistent manner. 1. INTRODUCTION Annually the CEMT (Confederation of European Maritime Technology Societies) to which ATMA is member, grants awards in recognition of the outstanding contribution made to the success of the European maritime industry by an individual, company or organisation. The 2013 award have been granted to 4 engineers of the Research Department of Bureau Veritas, so it appears of interest to remind, in their main lines, the studies which have been performed within this

2 department since some 20 years ago, in the domain of competence of the recipients: hydrodynamic and hydro-structure. The aim is not to detail all research studies performed during this period at Bureau Veritas. We shall remind only that the competences of this department extend on a large set of disciplines: hydrodynamic, mooring, hydrostructure, tests and measurements, sloshing, ice, structural integrity and risk, safety, energy and environment, design methodologies,. 2. HYDRODYNAMIC Referring hydrodynamic, the most important Bureau Veritas bringing is surely the development of the HydroStar software, seakeeping software which solves the potential equations of the fluid dynamic around floating or fixed structures. It is the result of research studies started in 1984 at the Ecole Centrale de Nantes during the Xia-Bo Chen Phd thesis, then continued at the Institut Français du Pétrole, then at Bureau Veritas since HydroStar is now used by all the Bureau Veritas technical teams, and by external clients (some fifty licences have been sold all around the world). We shall not describe here the software functions in detail but provide a quick view of some innovative functionalities which have been developed by Dr Chen and his team and which now make HydroStar one of the best computer code of this type in the world Efficient algorithms Since its design HydroStar has been thought to be quick and robust. The Green function is a very complex mathematical function, which is the basic brick used to solve the potential flows. If its formulation is known since very long time, the methods to calculate it may be different. The calculation of the Green function in HydroStar is based on a separation between a singular part (Rankine) and a regular part. To save calculation time, the regular part is approximated by a series of polynomials, the coefficients of which have been pre-calculated and integrated in the computer code. Figure 1 : Regular parts of the Green function with infinite depth (upper part) and complements for limited depth (lower part) Always in the aim to improve the calculation time, the used solvers to solve the integral equations have been optimised, and the software thought in a modular way Validations and comparisons Since its design, the HydroStar code results have been compared to existing analytical results of simple geometries (half sphere, cylinder, ) or to model test basin results for more realistic geometries. Today a testing procedure has been set up which compares automatically the results of each new version with reference results in view to verify the code non-regression. The HydroStar code results are also regularly compared to competing codes. The result is that HydroStar is a very robust code, as well for the meshing convergence than for the irregular frequencies treatment, all with a calculation speed rather higher than the average. The differences are more visible for the second order loads, as illustrated here after.

3 2.3. Second order loads HydroStar presents significant differences with its competitors by the innovations in the calculation of the second order loads. The classical theory considers two methods for the calculation of these loads. The near field method is based on a direct integration of the hull pressures. This method presents a very low convergence: it requires a very fine mesh to obtain good results. The far field method allows to solve this dependence to the mesh, but its application is limited to horizontal plane drift loads, and for only one floater. An intermediate method, called middle field, has been introduced in HydroStar. It uses a control surface which surrounds the floater and allows to obtain the advantages of the two previous methods: determination of all components of the loads, applicability to multifloaters simulation, drift loads and low frequency loads O( ), very good convergence with respect to the mesh. Figure 2 : Added masses and added damping comparison with a half sphere analytical results Figure 3 : Test-calculation comparison for a side by side tanker and FPSO Figure 5 : Control surface used by the mean field method Figure 4 : Different computer codes drift loads comparison

4 Figure 6 : Drift loads: mesh influence for the near and mean field methods The calculation of the second order low frequency loads, resulting of the interaction between two wave components with close frequencies is very time consuming. An approximated method, proposed by Newman, allows a simple calculation of these low frequency loads from the drift loads (mean loads). But, this approach is only valid for very low frequencies. An intermediate approach has been introduced in HydroStar, based on an innovative formulation, and it provides much better results than the Newman approximation, with a calculation time scarcely greater. to very bad previsions for some pathological cases. A possibility offered by HydroStar is to introduce a damping effect in the potential equations, not to simulate precisely the viscous flow, but to globally take into account the resulting energy dissipation. A damping area can be created on the free surface. It is, for example, the case when two ships side by side are simulated. In this case; the potential theory has a tendency to overestimate the wave height between the two ships. The introduction of a damping, which is introduced by HydroStar directly at the level of the integral equations which include the dissipation area, allows to obtain a realistic simulation of this case. Figure 7 : Comparison of the second order loads obtained with the complete QTF, the Newman approximation, and the approximation O( ) 2.4. Introduction of dissipation in the potential flows The potential theory presents the great advantage to allow very efficiently solving of the fluid dynamic equations, taking into account very precisely the inertial effects (waves, behaviour on wave, ), but locally it leads to neglect the dissipation from the viscous and turbulent origins, and so can lead Figure 8 : Test-calculation comparison of the surface motions between two barges The other application case is the tank sloshing simulation. The potential theory predicts, when the excitation frequency is equal to the tank free frequency, an infinite liquid motion associated to infinite loads. Effectively, there is no damping of potential origin. The introduction of a numerical dissipation on the tank walls allows to limit the sloshing to realistic values, and to allow the calculation of the ship dynamic coupled with her tanks (tanker, LNG, FPSO).

5 Figure 9 : Ship motion coupled with her tanks 3. HYDRO-STRUCTURE The developments in the hydro-structure area started at the beginning of the 2000s. It appears necessary at that time to be able to link the ship behaviour on wave performed with HydroStar with the structural calculations performed with a finite elements software (Nastran, Abaqus, ). The exploratory studies, initiated by Sime Malenica, lead in 2012 to the Homer software. This software transfers the calculated pressures by HydroStar to the ship structure mesh, then collects the stresses and the deformations calculated by the structural computer code. But this apparent simplicity hides in fact numerous more complex details to assure a robust and efficient link An original solution to transfer the pressures The coupling requires a transfer of the pressures calculated by the hydrodynamic code to the structure mesh. But in general the considered mesh to solve the hydrodynamic problem differs from the mesh used to solve the structural problem. The more intuitive method consists to interpolate the pressures of the hydrodynamic mesh toward the structural mesh, but this method is not robust as the interpolation introduces errors, and the loads obtained by pressure integration on the structural mesh are then different than the loads considered in the seakeeping code! The result is that the model is not correctly balanced for the finite element calculations. Figure 10 : Structure and hydrodynamic mesh of a container ship Homer uses an original method which comes from the core of HydroStar using the properties of the Green function. HydroStar is only used to solve the flow around the ship. Then it calculates the pressures directly at the Gauss points of the structural mesh (no interpolation). The global loads are then obtained by pressure integration on the structural mesh, and the ship motions are solved by Homer. This method assures a perfect equilibrium of the finite element model, whatever are the differences between the hydrodynamic and structural mesh. Homer is, as we know, the only hydro-structure software in the world that applies this method Hydro-elastic calculations For large size ships it has become necessary to take into account dynamically the ship girder main deformations. The method used by Homer is based on a modal approach. The method is not new, but it is used here with a 3D approach for the structure. The free modes of the dry ship are obtained from a modal analysis of the finite element model. The deformations are then transferred to the hydrodynamic model, and the ship motions and deformations are solved in the same way than for a rigid body, the only difference being that there are now N deformation modes instead of 6. The coupled elastic hydrodynamic behaviour solution leads to resonance peaks at the structural natural frequencies, which can induce a significant increase of the fatigue damage of the structural details. The modal approach has the advantage to allow to take into account some free mode resonances of the ship hull girder, but considers a cut-off of the ship deformation basis. The direct approach (also called quasi static) does not take into account the structure

6 dynamic, but take into account all degrees of freedom of the structural model. The approach used in Homer is hybrid; it combines the two previous approaches: the response is split between a quasi static response and a dynamic response. The quasi static response is calculated by a direct approach and the dynamic response by the modal approach. The so obtained total response combines the advantages of the two previous methods. presented can be used to simulate this phenomenon. To do so a simplified model for the impact loads is introduced, and the ship motions are solved in time domain, taking into account the hydrostatic deformations and incident wave non linear loads. Studies are always under progress to improve the impact load prediction. Figure 13 : Midship section bending moment with whipping 3.4. A very general software Homer, even if it has been developed to answer to an urgent need of hydroelastic simulations of container ships, can be applied for any kind of ship or offshore structures, and for any type of simulation (quasi static, springing, whipping, multi-bodies). Figure 11 : Free mode of a container ship and application of the deformation to the hydrodynamic mesh Figure 12 : Transfer function of a hatch corner stress 3.3. Whipping simulation The large container ships are subject to whipping, transient vibration induced by the wave impacts on the ship bow, with a possible significant increase of the stresses in the ship structure. The hydro-elastic model previously Figure 14 : Homer simulations of different units 4. SLOSHING The sloshing phenomenon in LNG carriers corresponds to the LNG motion induced by the ship motions during navigation or at fixed point. The sloshing is a multi scale phenomenon highly non-linear and can be violent, i.e., can induce damages in LNG, FLNG or FSRU tanks. Since the 2000s,

7 Pressure at sensor N 3 Global Torque Fy(N) research studies have been performed at Bureau Veritas by Mirela Zalar and Louis Diebold, based on the experimental and numerical approaches CFD calculations The target of the CFD (Computational Fluid Dynamics) is to evaluate the flow cinematic and the loads applied to the structure which lays behind the insulation system. The Flow3D code, used at the beginning has been substituted by the OpenFOAM code which is a parallel CFD code and an "open source" which can simulate complex flows (large scale simulations, RANSE model, compressible flows ). This calculation tool has been validated by numerous comparisons with test results. Within the scope of the European project Marstruct, a series of tests have been performed in a quasi 2D tank. The agreement between tests and OpenFOAM (CFD calculations) are excellent for the free surface elevation, the applied moment by the fluid on the tank walls and for the pressure as illustrated on figure 15. frequencies have been tested. The comparisons between the measured loads and the loads calculated by Flow3D and OpenFOAM are comparison -Flow3d-OpenFoam-EXP- test586 presented on figure 16. Amplitude=1m Frequency= Time (s) OpenFoam 1m Fy Flow3D 1m Fy EXP essai 586 Fy Figure 16 : Comparison of the global loads given by tests and CFD calculations (Flow3D & OpenFOAM) 20%H 1m f=0.854hz. The computers today allow to perform long simulations of several hours for irregular sea states, to extract the statistics of the loads and to compare them to the measured loads during tests. Here also the statistical comparison is very good. Figure 17 : Comparison of the global loads on irregular waves and convergence with different meshes (simulation of 3 hours) Case B - T=T0 - Sensor N 6 Comparison Experiments / Numerics Time (s) Num. Exp Case A - T=T0 - Global Torque Comparison Experiments / Numerics Figure 15 : Comparison between tests and CFD calculations of the surface elevation, pressure and global moment induced by the fluid on the tank Within the scope of a cooperation with Ecole Centrale de Nantes, BV performs its own sloshing test programs. Numerous filling configurations, motion amplitudes and Time (s) Exp. Num Dynamic gauges An innovation of Bureau Veritas in CFD calculations has been the development of a dynamic gauges module. In principle, the CFD calculations providing all data at each time step and in all mesh can provide a complete representation of the sloshing impacts on the tank walls. Unfortunately the CFD studies must be only concentrated on predefined areas (as for the sloshing test on small scale model) as the storage of all the data at each time step requires too much place on a storage disc. To solve this problem a specific post-treatment called "Dynamic gauge" has been developed at

8 Bureau Veritas. At each time step, the flow is analysed and the eventual sloshing impacts are detected and recorded when the pressure or the velocity normal to wall flow exceeds a threshold fixed by the user level. When an impact is detected (pressure or normal velocity exceeding the threshold) a "dynamic gauge" is created at the impact point. Each impact is then recorded within a time window also fixed by the user for a later verification. Finally this specific post-treatment tool allows to obtain a complete knowledge of all sloshing impacts on the tank walls and that during all the simulation time. The following figure 18 represents all sloshing impacts detected on the tank top during a simulation of a real sea state (i.e. irregular motions and simulation corresponding to a duration of 5 hours). Figure 19 : Sloshing test on hexapod Figure 18 : Map of impacts on the tank top for a sea state simulation during 5 hours at real scale with OpenFOAM 4.3. Independent tests Thanks to a cooperation with Ecole Centrale de Nantes and to GTT which provided a tank model, Bureau Veritas has been able to have its own tests in view to obtain its own expertise leading to the writing of the guidance note NI554 which describes the method to evaluate the sloshing loads and the tank wall scantlings. In particular this note indicates the tests to be performed, the pressure gauges to be used, the sampling frequencies, the identification of the pressure peaks, the type of statistical posttreatment 4.4. Sloshing statistics The applied approach for the LNG tank design was based at the beginning of the 2000s on a called short term approach, using only the 3h pressures obtained on some design sea states. The method is now a long term method taking into account all sea states encountered by the ship. This method requires the extrapolation of the test results on durations much longer than the test durations. The Weibull distribution is generally applied by industry as statistical adjustment for pressure samples. In view to determine if this Weibull law is the best adapted adjustment law for peak pressures, Bureau Veritas performed a specific test campaign to obtain a sample of 480 hours (96 tests of 5 hours), instead of the maximum 30 hours generally considered, and adjusted the pressure samples using different techniques: Weibull law, Pareto or GEV law, POT method, Maxima Block method. The studies have shown that the Weibull law leads systematically to underestimate the extreme pressures. On the opposite, the Pareto law, or the Maxima Block method allow a better statistical evaluation of the extreme pressures.

9 Significant wave height (m) on the same hypothesis in terms of environmental and operational conditions. It will be therefore even possible to use direct calculations to validate or modify rules. Figure 20 : Extrapolation of a 5h duration test with a Weibull and a Pareto law Figure 21 : Sloshing test of 480h duration 5. DESIGN METHODOLOGIES All these direct calculation software which allow to precisely simulate the hydrodynamic and structural response of a ship under a given sea state are of no use if they are not associated with a design methodology. The target of a direct calculation procedure, or a rule approach, is to provide the scantling of a ship or offshore structure versus the environmental and operational conditions which will be encountered. It is necessary to evaluate, on the whole life time of the unit, the extreme responses in terms of stresses, deformations or motions, and the fatigue damage. The rule procedures are more and more substituted, or complemented, by direct approaches, based on deterministic calculations (for example whipping calculation) or by tests (sloshing tests). To assure the consistency between these two approaches, it is necessary that both are based 5.1. Direct calculation methodology There is a great number of types of deterministic simulation models (HydroStar, Homer, CFD,.) from the simplest and less calculation time consuming models till the more precise and more time consuming ones. All are unfortunately not able to simulate the total life of a structure (25 years for a ship; more than 50 years for an offshore structure). It is therefore necessary to be able to simplify the encountered sea state statistics to be able to have shorter simulations. The most complete description is given by a statistic of the sea states classed versus significant height and peak period. These tables are used for a long term approach which consists to simulate all the life time of the unit. The use of this approach is limited to very simplified deterministic simulations (linear approach for example). > < 1 Total Total Up-crossing period Tz Figure 22 : IACS sea states table With certain hypothesis it is possible to reduce the sea states table to only some design sea states for which the extreme responses will be determined: This is the short term approach. It is sometime necessary to simplify even more the sea state description to consider only one wave, or one group of waves: It is then the design wave approach. Evidently, each time that we simplify the environmental description, accuracy is lost for the sea state representation, but is gained for the ship response simulation with the used of a more precise simulation software. The optimal design approach is the approach which will combine these different approaches to step by step reduce the simulation

10 conditions and increase the complexity of the simulations. Linear VBM / Rule value Wave Time (s) Figure 23 : Irregular design wave The extreme simplification of the sea conditions consists to delete the hydrodynamic calculations and to apply formulas which provide directly the loads to be applied to the structure. It is the approach selected for the classification society rules. These require to verify the structure with a limited number of loading cases, indicating each time the load to be applied. These loading cases are in fact a rule simplification of the design waves which are finally a simplification of some sea states that the ship will see during her life Direct calculation and rules development When the consistency is found between the direct calculation and the rules approach, it is possible to use the calculation for the rules evolution. A first example has been, within the IACS, to harmonize the tanker and bulk carrier rules. Bureau Veritas was in charge of a working group dealing with the scantling loads. At this occasion the application of the design waves has been generalised, and all the loading combination coefficients as well as the sea pressure have been calibrated applying this approach. The application of the design wave approach has also been applied to justify the selection of a limited number of the rule loading cases, for fatigue and for extreme responses. In addition, a refine analysis of the contribution of the stress cycles to the cumulative fatigue has shown, because more robust, that it is better to define the rule loads for fatigue with a probability level of 10-2 (there were before defined at 10-4 ). This approach, duly justified by calculations, is a major modification in the fatigue rule approach, and a lot of pedagogy and patience have been necessary to convince our IACS partners. Stress range s E+00 1E+02 1E+04 1E+06 1E+08 0 Cumulative number of cycles P ref * N 25 x = 1.15 x = 0.8 s ref N Probability Figure 24 : Weibull law distribution shape parameter influence on the fatigue life time Other works in progress within IACS planned to be finalized at the end of 2014, aim to redefine the rule vertical wave bending moment formula, using direct calculation results. The calculations effectively allow to identify the different components of the rule formula: wave parameter, non dimensional part, non linearity coefficient. The results show that the difference between the current formula and the calculation are more important for containerships that for tankers or bulk carriers. The new formula, which are always under discussion, aim to decrease this difference. Bulk Carriers Containerships LNG Carrier Cb / Cw Oil Tankers General Cargo Passengerships & Ro-Ro Figure 25 : Comparison between the rule vertical bending moment and the calculated moment by a direct approach

11 6. CONCLUSION The Research and Development works allow Bureau Veritas to develop its own tools and methods at the upper level of the State of the Art in view to acquire an independent expertise to develop its classification rules, answer to the client questions, and act within IACS and the maritime and offshore scientific community. Research and Development is based on a continuous questioning in view to maintain a newer as possible eye on the problems which we have to face. Within the future research axis in Bureau Veritas, the CFD is called to be extended. The CFD, which is used since some ten years to solve the ship resistance and ship hull optimisation has now reached a sufficient maturity to begin to be used for ship behaviour on waves, which requires to be able to simulate irregular sea state during long time. It will allow so, to more precisely answer to the slamming, green water on deck, ship behaviour on extreme waves, wave added resistance, local and violent flows problems. The aim for the coming years is to develop CFD tools and to include them in the global methodological approach which will have to efficiently apply the linear, non linear potential codes, and the CFD to obtain the more complete and precise design procedure. Another important research axis deals with the dynamic simulation of one or various offshore structures coupled with their mooring lines, risers, including the effects of current, wind, the second order loads, the wave non linearity, the large motion amplitudes. Finally, the rule development is always at the working agenda to allow to propose rules each time more precise, but also easier to be understood, and more coherent with the direct approaches. 7. REFERENCES 7.1. Hydrodynamic [1] Evaluation de la fonction de Green du problème de diffraction/radiation en profondeur d eau finie, 4èmes Journées de l Hydrodynamique, 1993 [2] On the Irregular Frequencies Appearing in Wave Diffraction-Radiation Solutions, S. Malenica and X.B. Chen, Int. J. of Offshore and Polar Eng., 1998, vol.8, no.2 [3] Hydrodynamics in Offshore and Naval Applications, Chen X-B., 6th International Conference on Hydrodynamics, Perth, Australia, 2004 [4] Middle-field formulation for the computation of wave-drift loads, J. Eng. Math., 2007, vol.59 [5] Second-Order Wave Loads on a LNG Carrier in Multi-Directional Waves, M. Renaud, F. Rezende, O. Waals, X.B. Chen and R. van Dijk, OMAE, 2008 [6] First and Second Order Wave-Current Interactions for Floating Bodies, C. Monroy, Y. Giorgiutti and X.B. Chen, OMAE, 2012 [7] Hydrodynamic issues of FLNG systems, X.B. Chen, L. Diebold and G. de Hauteclocque, OMAE, 2013 [8] A Practical O( ) Approximation of Low Frequency Wave Loads, C. Monroy, G. de Hautecloque and X.B. Chen, OMAE, Hydro-structure [9] Hydroelastic response of a barge to impulsive and non-impulsive wave loads, Malenica S., Molin B., Remy F. & Senjanovic I., 3rd Int. Conf. On Hydroelasticity, 2003 [10] Hydro structure interactions in seakeeping, Malenica S., International Workshop on Coupled Methods in Numerical Dynamics, 2007 [11] Consistent hydro-structure interface for evaluation of global structural responses in linear seakeeping, Malenica S., Stumpf E., Sireta F.X. & Chen X.B, OMAE 2008 [12] 3DFEM 3DBEM model for springing and whipping analyses of ships, Malenica S. & Tuitman J., RINA Conf. on Design and Operation of Container Vessels, 2008 [13] Fully coupled seakeeping, slamming and whipping calculations, Tuitman J.T. & Malenica S, Journal of Engineering for Maritime Environment Vol. 223, No M3, 2009

12 [14] Consistent hydro structure interface for partial structural model, Sireta F.X., Malenica S., Chen X.B. & Marchal N, Deep water Offshore Specialty Symposium, 2009 [15] Transfer of non-linear seakeeping loads to FEM model using quasi static approach, Tuitman J.T., Sireta F.X., Malenica S. & Bosman T.N, ISOPE 2009 [16] Local hydro-structure interactions due to slamming, Malenica S., Sireta F.X., Tomasevic S., Tuitman J.T. & Schipperen I., MARSTRUCT 2009 [17] Validation of the global hydroelastic model for springing & whipping of ships, Derbanne Q., Malenica S., Tuitman J.T., Bigot F. & Chen X.B, PRADS 2010 [18] Discussion on hydroelastic contribution to fatigue damage of containerships, Q. Derbanne, F.X. Sireta, F. Bigot and G. de Hauteclocque, 6 th Int. Conf. On Hydroelasticity, 2012 [19] Global Hydroelastic Ship Response: Comparison of numerical model and WILS model tests, F. Bigot, Q. Derbanne, F.X.Sireta, S. Malenica, ISOPE 2011 [20] Hydroelastic response of a ship structural detail to seakeeping loads using a top-down scheme, FX Sireta, Q. Derbanne, F. Bigot, S. Malenica and E. Baudin, OMAE Sloshing [21] Dynamic coupling of seakeeping and sloshing, S. Malenica, M. Zalar & X.B. Chen, ISOPE 2003 [22] Sloshing effects accounting for dynamic coupling between vessel and tank liquid motion, M. Zalar, L. Diebold, E. Baudin, J. Henry and X.B. Chen, OMAE 2007 [23] Design Sloshing Loads for LNG Membrane Tanks, NI554 DT R00 E, Guidance Note, May 2011 [24] Statistical Post-Processing of a Long Duration Test, B. Fillon, L. Diebold, J. Henry, Q. Derbanne, E. Baudin and G. Parmentier, ISOPE 2011 [25] Experimental and Numerical Investigations of Internal Global Forces for Violent Irregular Excitations in LNGC Prismatic Tanks, L. Diebold, N. Moirod, E. Baudin and T. Gazzola, ISOPE 2011 [26] Détermination des Chargements dus au Sloshing. Application aux unités flottantes d opération et de liquéfaction de gaz (FLNG, FSRU), L. Diebold, N. Moirod, T. Gazzola and E. Baudin, ATMA 2012 [27] Dynamic Probes: an on-the-fly CFD Plug-in for Sloshing Impact Assessment, T. Gazzola and L. Diebold, ISOPE 2013 [28] Bureau Veritas Sloshing Model Tests & CFD Calculations within ISOPE Benchmark, E. Baudin, L. Diebold, B. Pettinotti, J.M. Rousset and M. Weber, ISOPE 2013 [29] Extreme Values Theory Applied to Sloshing Pressure Peaks, B. Fillon, J. Henry, L. Diebold and Q. Derbanne, ISOPE 2013 [30] Statistical Behaviour of Global and Local Sloshing Key Parameters, L. Diebold, Q. Derbanne and T. Gazzola, ISOPE Long term methodologies [31] Long-term non-linear bending moment prediction, Q. Derbanne, J.F. Leguen, T. Dupau, E. Hamel, OMAE 2008 [32] Evaluation of Rule-Based Fatigue Design Loads Associated at a New Probability Level, Q. Derbanne, F. Rezende, G. de Hautecloque and X.B. Chen, ISOPE 2011 [33] Comparison of Design Wave Approach and Short Term Approach with Increased Wave Height in the Evaluation of Whipping Induced Bending Moment, Derbanne Q., Bigot F. and de Hauteclocque G, OMAE 2012 [34] Comparison of different equivalent design waves with spectral analysis, G. de Hauteclocque, Q. Derbanne and A. El-Gharbaoui, OMAE 2012

13 [35] Non Linearity of Extreme Vertical Bending Moment: Comparison of Design Wave Approaches and Short Term Approaches, Q. Derbanne; G. de Hauteclocque and T. Mienhaou, OMAE 2013 [36] Non Linearity of Extreme Vertical Bending Moment: Discussion on the Existing Rule Formulation, Q. Derbanne, G. de Hauteclocque and T. Mienhaou, OMAE 2013 [37] Design Wave Selection for Strength Assessment of Floating Structures, Q. Derbanne, G. de Hauteclocque, A. El- Gharbaoui, P. de Belizal, PRADS 2013