The term "climate services" is commonly used to refer to the generation of climate information, their transformation according to user needs and the subsequent use of the information in decision making processes. More generally, the concept also involves contextualization of information and knowledge. In the following a series of examples from the marine sector is described covering the generation, transformation and the use of climate information in decision making processes while contextualization is not considered. Examples comprise applications from naval architecture, offshore wind and more generally renewable energies, shipping emissions, and tidal basin water exchange and eutrophication levels. Moreover effects of climate change on coastal flood damages and the need for coastal protection are considered. Based on the analysis of these examples it is concluded that reliable climate information in data sparse regions is urgently needed, that for many applications historical climate information may be as or even more important as future long-term projections, and that the specific needs of different sectors substantially depend on their planning horizons.
For the analysis of loads and motions of marine structures in harsh seaways precise information about the hydrodynamics of waves is required. While the surface motion of waves can easily be measured in physical wave tanks other critical characteristics such as the instantaneous particle velocity and acceleration as well as the pressure field, especially under the wave crest are difficult and time-consuming to obtain. Therefore a new method is presented to approximate the wave potential of a given instantaneous wave contour. Numerical methods — so called numerical wave tanks (NWTs) — are developed to provide the desired insight into wave hydrodynamics. A potential theory method based on the Finite Element method (Pot/FE), a RANSE (Reynolds-Averaged Navier-Stokes Equations) method applying VOF (Volume of Fluid) and a combination of both is utilized for the simulation of different model wave trains. The coupling of both CFD (computational fluid dynamics) solvers is a useful approach to benefit from the advantages of the two different methods: The Pot/FE solver WAVETUB (wave simulation code developed at Technical University Berlin) allows a very fast and accurate simulation of the propagation of nonbreaking waves while the RANSE/VOF solver has the capability of simulating breaking waves. Two different breaking criteria for the detection of wave breaking are implemented in WAVETUB for triggering the automated coupling process by data transfer at the interface. It is shown that an efficient method for the simulation of breaking wave trains including wave-structure interaction in 2D and 3D is established by the coupling of both CFD codes. All results are discussed in detail.
While the offshore climate in the North Sea bears a great potential for the exploitation of reliable and powerful wind energy it poses a challenge for the constructors of offshore wind farms. Large heavy lift jack-up vessels (HLJV) are employed to transport the components of the wind energy converters to the offshore location. After a preloading and jacking procedure, subsea lifts of tripod foundations weighing up to 950tons as well as tower and nacelle installations at large heights need to be undertaken. As typical offshore wind farms consist of 80 or more separate wind turbines the installation works are conducted in a serial manner — often through the winter season. Thus, many critical offshore operations are conducted consecutively on the basis of daily or weekly weather reports. These operations cannot rely on optimal weather conditions therefore planning and engineering has to cover appropriate wind and wave conditions taking into account contingencies for uncertainties in the reliability of weather windows as well as in the soil conditions. This paper shows how the weather criteria derived from numerical seakeeping and structural simulations are taken into a project simulation model covering 90 separate serial installations. Based on hindcast re-analyses installation simulations are conducted in multi-seasonal weather scenarios. This enables the quantification of the suitability of a particular marine spread and its associated installation processes in combination. The risk profile of weather related delays are derived.
The realistic modelling of velocity and pressure fields in steep, irregular seaways is still a challenging task, especially when extreme events such as freak waves are under investigation. Conventional wave theories provide fast and reliable results while CFD-codes based on RANSE or potential theory are gaining more acceptance for simulating water waves even though they are still considerably time consuming. This paper presents an approach to approximate irregular wave trains with known surface elevations by interacting Stokes waves of up to third order. This is a fast method to determine the wave potential of wind generated waves for long lasting wave registrations with arbitrary origin. The technique is applied to a steep breaking wave package as well as to a realization of a wave train in a wave tank (scale 1:120) which contain a measured extreme wave sequence. Here, special attention is paid to the distinction between the kinematics of the wave crests in extremely high waves and their surrounding irregular wave field. The predicted wave kinematics are validated by experiments employing particle velocity measurements (by Laser Doppler Velocimetry) as well as by pressure recordings. Kinematics of breaking waves are not covered by concurrent analytical wave theories. To address this deficiency a coupling mechanism between a conventionally determined velocity field with a RANSE/VoF-method is applied.
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