Hydromechanical Analysis of Offshore Structures

Clauss, Günther F.; Lehmann, Eike; Östergaard, Carsten

doi:10.1007/978-1-4471-3193-9_3

Cited by 6 publications

(5 citation statements)

References 22 publications

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“…The maximum force is then calculated as the maximum value over a wave period. C M and C D are both functions of Keulegan-Carpenter number [20], a measure for the ratio between the wave height and the cylinder diameter, and Reynolds number, in addition to an outer surface condition expressed in terms of the degree of roughness [2,21]. It should be noted that C D increases with increasing roughness, whereas C M decreases with increasing roughness.…”

Section: Methodsmentioning

confidence: 99%

Assessing Extreme Environmental Loads on Offshore Structures in the North Sea from High-Resolution Ocean Currents, Waves and Wind Forecasting

Skliris

Marsh

Srokosz

et al. 2021

JMSE

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The fast development of the offshore energy industry becomes an essential component of resilient economies in most of the countries around the North Sea, addressing an increasing demand for cost-efficient and environmentally safe energy sources. Offshore wind farms are planned to be installed further away from the coasts to ensure stronger and more stable wind resources in this region. Oil and gas extraction infrastructures are also planned to move into deeper areas of the continental shelf and continental shelf slopes to explore new fields. These deeper areas of the ocean are characterised by harsh environmental conditions: stronger winds, larger waves and strong shelf slope currents, inducing considerably larger loads on offshore structures. This study brings together operational physical oceanography and the mathematics of fluid-structure interactions to estimate the likelihood of extreme environmental loads on offshore structures in the North Sea. We use the state-of-the-art Met Office high resolution ocean forecasting system, which provides high-frequency data on ocean and tidal currents, wave heights and periods and winds at a ~7 km horizontal resolution grid, spanning the North–West European Shelf. The Morison equation framework is used to calculate environmental loads on various types of offshore structures that are typically employed by the offshore industries in the North Sea. We use hourly data for a 2-year period to analyse the spatio-temporal variability of mean and extreme hydrodynamic loads and derive the relative contributions of currents, waves and winds in the region. The results indicate that waves dominate extreme hydrodynamic forces on the shallow shelf, whereas the current contribution is important at the shelf break and in the English Channel.

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Section: Methodsmentioning

confidence: 99%

Assessing Extreme Environmental Loads on Offshore Structures in the North Sea from High-Resolution Ocean Currents, Waves and Wind Forecasting

Skliris

Marsh

Srokosz

et al. 2021

JMSE

View full text Add to dashboard Cite

show abstract

“…Carpenter number [22,23], a measure for the ratio between the wave height and the cylinder diameter, and Reynolds number (Re). In addition, 𝑪𝑪 𝑫𝑫 increases with increasing local surface roughness of the structure, whereas 𝑪𝑪 𝑴𝑴 decreases with increasing roughness.…”

Section: Methodsmentioning

confidence: 99%

Safer Operations in Changing Ice-Covered Seas: Approaches and Perspectives

Aksenov

Rynders

Feltham

et al. 2022

IUTAM Symposium on Physics and Mechanics of Sea Ice

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The last decades witnessed an increase in Arctic offshore operations, partly driven by rising energy needs and partly due to easing of sea ice conditions and improved accessibility of shipping routes. The study examines changes in sea ice and ocean conditions in the Arctic with their implications for off-shore safety. The objective of the research is to develop a basis for forecasting technologies for maritime operations. We assess loads on off-shore structures from sea ice and ocean in centennial climate future projections and implications for the accessibility and future Arctic shipping. As a test case, we calculate loads on a tubular structure of 100-m wide and 20-m tall, similar to installations in the Beaufort Sea in the 1980s.With sea ice retreating, loads are predicted to increase from ~0.1 x 10 6 Newton (MN) at present to ~50-200 MN in the 2090s, primarily 2 due to wave loads. This study asserts the need for new approaches in forecasting to make marine operations in the Arctic safer.

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“…Figure 8 Breaking wave height and regions of validity of various gravity water waves' theories (Clauss et al 1992) lar sea state parameters. The phases were randomly generated and differ within each set of parameters but are constantly plugged for each set.…”

Section: Transitional Water Deepwatermentioning

confidence: 99%

Experimental Study on the Effect of Extreme Waves on a LNG Carrier

Klein

Wang

Clauss

et al. 2023

J. Marine. Sci. Appl.

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This paper presents a comprehensive experimental study on the effect of extreme waves on a LNG carrier. The LNG carrier model was equipped with a variety of sensors to measure motions, green water height on deck as well as local and global loads. Experiments in transient wave packets provided the general performance in waves in terms of response amplitude operators and were accompanied by tests in regular waves with two different wave steepness. These tests allowed detailed insights into the nonlinear behavior of the vertical wave bending moment in steep waves showing that green water on deck can contribute to a decrease of vertical wave bending moment. Afterwards, systematic model tests in irregular waves were performed to provide the basis for statistical analysis. It is shown that the generalized extreme value distribution model is suitable for the estimation of the extreme peak values of motions and loads. Finally, model tests in tailored extreme wave sequences were conducted comparing the results with the statistical analysis. For this purpose, analytical breather solutions of the nonlinear Schrödinger equation were applied to generate tailored extreme waves of certain critical wave lengths in terms of ship response. Besides these design extreme waves, the LGN carrier was also investigated in the model scale reproduction of the real-world Draupner wave. By comparing the motions, vertical wave bending moment, green water column and slamming pressures it is concluded that the breather solutions are a powerful and efficient tool for the generation of design extreme waves of certain critical wave lengths for wave/structure investigations on different subjects.

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Hydromechanical Analysis of Offshore Structures

Cited by 6 publications

References 22 publications

Assessing Extreme Environmental Loads on Offshore Structures in the North Sea from High-Resolution Ocean Currents, Waves and Wind Forecasting

Assessing Extreme Environmental Loads on Offshore Structures in the North Sea from High-Resolution Ocean Currents, Waves and Wind Forecasting

Safer Operations in Changing Ice-Covered Seas: Approaches and Perspectives

Experimental Study on the Effect of Extreme Waves on a LNG Carrier

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