| Autor: |
Hai Hua Xu, Jing Liu, Kie Hian Chua, Ankit Kumar Choudhary, Anis Altaf Hussain, Youngkook Kim, Yali Zhang, Andrew Pang, Pei Feng Ma, Aziz Amirali Merchant |
| Rok vydání: |
2018 |
| Předmět: |
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| Zdroj: |
Day 3 Wed, May 02, 2018. |
| Popis: |
It is challenging to predict the air gaps of floating offshore structures due to the property of ocean waves and induced motions of the structures. Linear analysis based on potential flow theory is common to be used for air gap evaluations before carrying out air gap model tests with typical 3-hour irregular wave. CFD (Computational Fluid Dynamics) simulations are getting popular for the offshore industry to reduce uncertainty of the design. However, simulation of short-term irregular sea for the air gap evaluation using CFD is time consuming. Because non-extreme events are not of interest to the designers for air gap assessment, combination of focus wave, based on NewWave theory, and probability distribution of wave crest is used to generate the most probable extreme wave and applied for the air gap evaluation in this study. The developed extreme wave is first evaluated against the undisturbed waves in the model tests. Several wave crest distributions are compared to find the most suitable one for target wave when used with NewWave theory. Due to the non-linearity of NewWave and numerical dissipation, best practice methodologies are investigated to obtain the required target wave. By applying such a design wave in CFD, the air gap of a semisubmersible was assessed. The responses of the floater, i.e. motions and relative wave elevations, are compared against the several extreme events observed in irregular model test to evaluate the developed methodology. This study demonstrates how the focus wave technique can be used in CFD for air gap assessment instead of a 3 hour short term simulation. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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