{"title":"用短时设计波模拟极端二阶浪涌响应的下部结构试验案例","authors":"","doi":"10.1016/j.apor.2024.104232","DOIUrl":null,"url":null,"abstract":"<div><p>This work aims to determine the wave conditions that generate maximum surge response excited predominantly by second-order difference frequency forces. Standard narrow-band wave conditions have random phase components and obtaining the maximum surge response requires long sea-state durations to cover all combinations and correspondingly long computation times using second-order diffraction–radiation models. Multiple 3-hour random sea-states are typically used to evaluate the expected extreme response. The maximum force may be obtained by shifting phases to be equal between component pairs with a frequency difference equal to the structure’s surge natural frequency. However, this work shows that such an approach gives a highly transient force and the lightly damped surge displacement response does not approach a representative maximum value. The larger motion responses may be achieved by sequential wave groups and here we use a genetic algorithm to optimise the phase distribution to give more regular low-frequency excitation in relatively short sea-state durations, less than 1 h. This is demonstrated with a one degree-of-freedom Fourier model. The method is applied to a lightly-moored spar substructure and compared with an experimentally validated standard six degree-of-freedom time domain model (Orcaflex) showing satisfactory agreement.</p></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":null,"pages":null},"PeriodicalIF":4.3000,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0141118724003535/pdfft?md5=a644e96828c2b8a4298ea174618821d9&pid=1-s2.0-S0141118724003535-main.pdf","citationCount":"0","resultStr":"{\"title\":\"Short-duration design waves for modelling of extreme second-order surge response with spar substructure test case\",\"authors\":\"\",\"doi\":\"10.1016/j.apor.2024.104232\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>This work aims to determine the wave conditions that generate maximum surge response excited predominantly by second-order difference frequency forces. Standard narrow-band wave conditions have random phase components and obtaining the maximum surge response requires long sea-state durations to cover all combinations and correspondingly long computation times using second-order diffraction–radiation models. Multiple 3-hour random sea-states are typically used to evaluate the expected extreme response. The maximum force may be obtained by shifting phases to be equal between component pairs with a frequency difference equal to the structure’s surge natural frequency. However, this work shows that such an approach gives a highly transient force and the lightly damped surge displacement response does not approach a representative maximum value. The larger motion responses may be achieved by sequential wave groups and here we use a genetic algorithm to optimise the phase distribution to give more regular low-frequency excitation in relatively short sea-state durations, less than 1 h. This is demonstrated with a one degree-of-freedom Fourier model. The method is applied to a lightly-moored spar substructure and compared with an experimentally validated standard six degree-of-freedom time domain model (Orcaflex) showing satisfactory agreement.</p></div>\",\"PeriodicalId\":8261,\"journal\":{\"name\":\"Applied Ocean Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":4.3000,\"publicationDate\":\"2024-09-20\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.sciencedirect.com/science/article/pii/S0141118724003535/pdfft?md5=a644e96828c2b8a4298ea174618821d9&pid=1-s2.0-S0141118724003535-main.pdf\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Applied Ocean Research\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0141118724003535\",\"RegionNum\":2,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ENGINEERING, OCEAN\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Applied Ocean Research","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0141118724003535","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, OCEAN","Score":null,"Total":0}
Short-duration design waves for modelling of extreme second-order surge response with spar substructure test case
This work aims to determine the wave conditions that generate maximum surge response excited predominantly by second-order difference frequency forces. Standard narrow-band wave conditions have random phase components and obtaining the maximum surge response requires long sea-state durations to cover all combinations and correspondingly long computation times using second-order diffraction–radiation models. Multiple 3-hour random sea-states are typically used to evaluate the expected extreme response. The maximum force may be obtained by shifting phases to be equal between component pairs with a frequency difference equal to the structure’s surge natural frequency. However, this work shows that such an approach gives a highly transient force and the lightly damped surge displacement response does not approach a representative maximum value. The larger motion responses may be achieved by sequential wave groups and here we use a genetic algorithm to optimise the phase distribution to give more regular low-frequency excitation in relatively short sea-state durations, less than 1 h. This is demonstrated with a one degree-of-freedom Fourier model. The method is applied to a lightly-moored spar substructure and compared with an experimentally validated standard six degree-of-freedom time domain model (Orcaflex) showing satisfactory agreement.
期刊介绍:
The aim of Applied Ocean Research is to encourage the submission of papers that advance the state of knowledge in a range of topics relevant to ocean engineering.