A numerical simulation of the hydrodynamic interaction and attitude of a ship and two ships of different sizes navigating in parallel in waves were carried out in this paper. The study of the two ships navigating in parallel is of great significance in marine replenishment. This paper used in house computational fluid dynamics (CFD) code to solve unsteady RANS equation coupled with six degrees of freedom (6DOF) solid body motion equations. URANS equations are solved by finite difference method and PISO algorithm. Structured grid with overset technology have been used to make computations. Turbulence models used the Shear Stress Transport (SST) k-ω model. The method used for free surface simulation is single phase level set. In this paper, two DTMB 5415 with different scales are selected for simulation analysis. This paper analyzed the impact of the big ship on the small ship when the two ships were navigating in parallel. This paper also analyzed the relationship between interaction and velocity between hulls, which has certain guiding significance for the ship’s encounter on the sea.

Accurate prediction on the behaviour of the nonlinear waves in a coastal environment is vital to the safe design and performance of coastal defence. This paper is concerned with the description of tsunami wave-island interaction, and includes both linear and nonlinear modelling of the maximum free surface motion arising within distorted flow field. A deterministic nonlinear effect on the predicted maximum runup is examined using a Boussinesq-type model. Statistics of the predicted maximum leading-crest motion are obtained and discussed in light of linear diffraction theory. The results show that the predicted maximum runup and free surface motion by the quaternary-islands is affected by nonlinear wave transformation. The numerical simulations suggest that the present model describes the wave field very accurately even for extreme events. The present study provides a critical insight into the free surface elevation maxima at surf zone, thus safeguarding the structure design.

This paper describes a major collaborative project funded through the European Union which seeks to accelerate the adoption of ocean energy systems through providing a rational suite of protocols that will: (i) help to match technology and scale of deployment to site specific considerations; (ii) define acceptable methodologies to evaluate the environmental consequence of deployment; (iii) develop techniques for equitable comparison of the economic potential; for the deployment of small to medium arrays. EquiMar involves 23 European partners, including scientists, engineers, ecologists and developers. Funded through the European Commission 7 th Framework Programme [1] (grant agreement 213380), this €5.5 million project aims to produce a suite of protocols that will enable a broad range of stakeholders to judge the variety of technologies in wave and tidal energy on a level playing field. The protocols will reflect the entire development cycle of a marine device: resource assessment and site selection; fundamental engineering design; scaling up and deployment; environmental impact and economic assessment. The project has now been running for 12 months. This paper reviews the intended work over the three year project, but focuses on the development of “high level” documents that will describe the aims and remit of the individual protocols. The high level protocols were conceived to meet two fundamental requirements. EquiMar is an ambitious project in terms of both scope and number of collaborators. There is a need to maintain consistency and clarity as each protocol/ guideline is developed. The high level protocols will serve as a template for the detailed specifications, clarifying content, identifying gaps and links within the overall work and finally will help to maintain focus on the final goals. Externally the high level documents will provide a mechanism for engagement of the many stakeholders. Early feedback on the direction and coverage of the protocols is fundamental to achieving, where practica, a consensus from the diverse ocean energy community. Based on the practices of an international Certifying Agency (DNV) it is intended that the protocols will be fit for guidance and incorporation into proposed international standards. This paper aims to increase dissemination and provoke comment from the International marine community in order that that the final documents will be fit for purpose by reflecting the considered opinion of as wide a body of relevant contributors as is possible, and act as a catalyst to help deliver the potential for marine renewable energy on the international stage.

Sea waves are random in nature as they propagate with different frequencies and in different directions. In literature, there are several studies about dynamic behavior of marine structures under random waves in frequency domain, but little or nothing has been done about wave directionality. In this paper, the behavior of a typical jack-up platform operating in Caspian Sea is studied. In order to model the interaction between spudcan and surrounding soil, it was modeled separately by PLAXIS software. The applied soil properties are based on the field measurements. The results from plastic analyses show that they can differ up to 18 percent compared with those obtained based on the recommendations of API. A 3D model of Iran-Khazar Jack-up was studied using ANSYS software. All elements of triangular legs were modeled by PIPE59 elements and the results obtained from previous step were used to model nonlinear interaction of spudcan footings. The wave and current characteristics are based on the field data. The time-history records of earthquake used in this research are based on Manjil earthquake related to the same area. Nonlinear dynamic analyses including large deflection and material non-linearity was performed. The temporal variation of displacement at deck level was compared under solely wave or earthquake loading and simultaneously acting wave and earthquake loading assuming to be in the same direction and in different directions. It is found that when earthquake loading is applied simultaneously with wave loading in the same direction, displacements are less than wave loading alone. However, when they are applied in different directions, especially when the direction of applied earthquake differs about 30 or 90 degrees with respect to wave direction, displacements become larger. In addition, the effect of wave directionality on the maximum displacement of structure was considered.

This paper presents highlights of the report of the 16 th International Ship and Offshore Structure Congress (ISSC) I.1 Environment Committee presented in August 2006 in Southampton, UK. Subjects addressed include notable accomplishments in the study of the marine environment pertinent to the design and operation of ships and offshore structures. These include advances in the past three years with respect to sensing, modeling and analysis of environmental data, discussion of rogue waves, climate change and parametric roll, and recommendations for further research.

The nonlinear dynamic response of jacket-type offshore platform (which has been installed in Persian Gulf) under simultaneously wave and earthquake loads is conducted. The interaction between soil and piles is modeled by Konagai-Nogami model. The structure is modeled by finite element method. The analyses include models with the longitudinal component of earthquake and wave in the same direction and in different directions. The results indicate that when the longitudinal component of earthquake and wave are in the same direction, wave may reduce the response of studied platform and when they are in different directions, in some cases there is an increase in the response of platform.

The present paper describes the behavior of a vertical riser in waves, currents and which is excited by displacements at the riser top. Fundamental equations for riser behavior are described and the Ferrari&Bearman model [4] is applied to estimate hydrodynamic load for “in-line” and transverse directions of the riser. Solution for riser behavior is obtained in time domain, calculations are performed for deepwater field production scenario and discussions are addressed. The influence of variation of riser diameter and drag coefficient along its length, the presence of floaters and effect of petroleum fluid flowing in the riser are investigated. Moreover, effects of the upper and bottom end conditions of the riser on its behavior are also taken into account in the analysis.

For the design of offshore wind turbines exposed to wind and wave loads, the method of combining the wind load and the wave load is significantly important to properly calculate the maximum stresses and deflections of the towers and the foundations 1) . Similarly, for the analysis of the fatigue damage critical to the structural life, the influences of combined wind and wave loads have not been clearly verified. In this paper fatigue damage at the time of typhoon passing is analyzed using actually recorded data, though intrinsically long-term data more than 10years should be used to properly evaluate the fatigue damage. This paper concludes that the fatigue damage of the tower caused by the wave load is not substantial and, thus, the fatigue damage by the combined wind and wave load is only 2–3% larger than the simple addition of the independent fatigue damages by the wind and the wave loads. The fatigue damage of the tower top, which is required to reduce the diameter in order to minimize the aerodynamic confliction with blades, is larger than that of the tower bottom. The fatigue damage at the foundation by the combined wind and wave load is 25% larger than the simple addition of the wind and wave damages, as the foundation is directly exposed to the wave load. For the foundation, the proper structural section can be designed in order to improve the structural performance against fatigue.

Based on the hindcast data of 21 storm processes, a Poisson bivariate Logistic extreme value distribution is proposed to estimate the joint probability of extreme wind speed and extreme significant wave height in the storms, the frequency of which can be described by a Poisson distribution. In order to calculate the structural response of an ocean platform, such as base shear, three methods are utilized, namely (I) traditional univariate frequency analysis method; (II) base shear return value method; (III) wind-wave joint probability method. Calculation results show that the proposed statistical model is suitable for the design of fixed platforms in the storm-influenced area.