CAREER: Irregular Environmental Loading and Response of Offshore Structures

最近计算机和传感器硬件的发展极大地提高了现场数据收集能力，超过了优化利用这些数据的新方法的发展。长期以来，海洋结构的水动力载荷和流体-结构相互作用一直是计算机密集型确定性计算的目标，但这些过程本质上是随机的，没有足够的方法来量化结构载荷和响应。在这里，随机过程理论、结构动力学、流体动力学和测量数据解释将相结合，以改进海上结构的设计方法，并使确定性流体动力学理论能够与全尺寸测量数据相验证。提出了预测浅水和极深水流固耦合的新方法和相关的数值工具。示例应用将与海上风力涡轮机和海上立管的负载和响应预测有关。海洋立管是海底和海面之间输送流体的垂直管道。PI在斯坦福大学的博士研究综合了流体结构相互作用、随机振动和极值理论，并与测量数据进行了广泛的比较。他在海上结构设计和建造的先进方法方面也有十年的行业经验，他认为需要新的方法来量化海上结构的环境载荷和响应。智力优势：本研究增加了对浅水和深水流固相互作用的基本理解，开发了新的工程方法，并应用这些新方法开发新的数值工具，用于水动力理论的设计和测试。风力发电机的工作将统计方法和流函数波浪理论与新的动态数值模型相结合，以更好地预测结构上的波浪载荷，并更好地理解风、波和结构之间复杂的相互作用。海洋立管的工作解决了涡激振动（VIV）问题，这是一个流固耦合问题，在大电流下主导着海洋长立管的设计。将开发一种新的随机振动方法，其中使用从测量数据建立的统计分布来定量评估水动力理论的有效性。新方法可用于各种结构振动应用。具体研究目标包括：(1)基于流函数理论，建立一种新的不规则波浪模拟方法来预测海浪剖面和运动；(2)建立新的随机过程模型，将新的不规则波浪方法与不规则风特征相结合，预测海上风力发电机的极端载荷；(3)将(1)和(2)的结果与全尺寸测量数据进行严格比较，以验证新方法；(4)建立了极深水海洋立管的确定性动力学模型；(5)根据实测数据推导出立管加速度的统计分布；(6)利用(4)和(5)的结果定量评估假设的水动力理论解释观测到的加速度数据的可能性；(7)新方法的其他应用。更广泛的影响：通过更好地理解结构与环境之间的复杂相互作用，拟议的工作将对海上风力涡轮机和海洋立管的未来设计产生直接影响。这两个领域都与当前和未来的世界能源供应有关。该项目还将加强两种不同技术文化之间的思想交流：欧洲主导的海上风能和美国主导的深水海上石油生产。具体的教育和更广泛的影响目标包括：(1)开发近海和近岸结构动力学和流固相互作用的新课程，包括本研究的一些成果；(2)通过美国国家科学基金会资助的“盖茨”项目，向历史上代表性不足和经济困难的理工科学生伸出援手；(3)通过现有的海上夏令营项目，与K-12学生和教育工作者进行接触，该项目迄今已在TAMUG接待了超过10,000名K-12学生和1,000名K-12教师；(4)在重要的新兴技术领域培养有前途的研究生。

Abstract for: CAREER: Irregular Environmental Loading and Response of Offshore Structures, CMS proposal 0448730PI: Sweetman, Texas A&M - GalvestonRecent computer and sensor hardware developments have dramatically increased field datacollection capabilities, outpacing development of new methodologies to make optimal use ofthese data. Hydrodynamic loading and fluid-structure interaction on offshore structures havelong been targeted with computer-intensive deterministic calculations, but these processes areinherently stochastic, for which no adequate methodologies exist to quantify structural loads andresponse. Here, random process theory, structural dynamics, hydrodynamics, and measured data interpretation will be combined to improve design methods for offshore structures and enable verification of deterministic hydrodynamic theories with full-scale measured data. New methodologies and associated numerical tools for prediction of fluid-structure interaction in both shallow and very deep waters are proposed. Example applications will be worked in detail relevant to load and response predictions for offshore wind turbines and marine risers. Marine risers are the vertical pipes carrying fluids between the sea-floor and sea-surface. The PI's doctoral research at Stanford integrated fluid-structure interaction, random vibrations and extreme value theory and included extensive comparison with measured data. He also has ten years of industry experience in advanced methods for design and construction of offshore structures where he saw the need for new ways to quantify environmental load and response of offshore structures.Intellectual Merit: This research increases the fundamental understanding of fluid-structureinteraction in both shallow and very deep waters, develops new engineering methods, and applies these new methods to develop new numerical tools for use in design and test of hydrodynamic theories. The wind turbine work combines statistical methods and stream function wave theory with a new dynamic numerical model to better predict wave loading on the structure and to better understand the complicated interaction between winds, waves, and the structure. The marine riser work addresses vortex-induced vibration (VIV), a fluid-structure interaction problem dominating design of long marine risers in high currents. A new random vibration methodology will be developed where statistical distributions built from measured data are used to quantitatively assess the effectiveness of hydrodynamic theories. The new methodology may find use in various structural vibration applications.Specific research goals include: (1) develop a new irregular wave simulation methodologyto predict ocean wave profiles and kinematics based on stream function theory; (2) developa new random process model to combine the new irregular wave methodology with irregularwind characterizations to predict extreme loading on offshore wind turbines; (3) critically comparethe results from (1) and (2) with full-scale measured data to verify the new methods; (4)develop a deterministic dynamic model of a marine riser in very deep water; (5) develop statisticaldistributions of riser accelerations from measured data; (6) use results of (4) and (5) toquantitatively assess the likelihood that hypothesized hydrodynamic theories explain observedacceleration data; and (7) other applications of the new methodology.Broader Impact: The proposed work will have direct impact on future design of offshore windturbines and marine risers by providing a better understanding of complex interactions betweena structure and its environment. Both of these areas are relevant to present and future worldenergy supplies. The project will also enhance cross-pollination of ideas between two differenttechnical cultures: European-dominated offshore wind energy and the US-dominated deep-wateroffshore oil production.Specific educational and broader impact goals include: (1) development of a new course in off-shore and near-shore structural dynamics and fluid-structure interaction including some resultsfrom this research; (2) outreach to science and technology students from historically underrepresented and financially challenged situations through the NSF-funded "GATES" program; (3) outreach to K-12 students and educators through the existing Sea Camp Program, which has hosted over 10,000 K-12 students and 1,000 K-12 teachers at TAMUG to date, and (4) education of promising graduate students in important emerging technical areas.