Advanced FEM for Strongly Coupled Fluid-Structure Interactions in Offshore Applications Including Low and Zero Mass Ratios

用于海上应用（包括低质量比和零质量比）强耦合流固耦合的先进有限元法

• 批准号: RGPIN-2014-06314
• 负责人: ETIENNE, Stéphane
• 金额: $ 1.75万
• 依托单位: École Polytechnique de Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=650326
• 关键词: Advanced; FEM; Strongly; Coupled; Fluid

Fluid-Structure Interactions (FSI) are critical to the design of many engineering systems. From sea-worthiness to airplane maneuverability, nearly all mechanical systems involve a certain degree of coupling between structures and fluid flows. At the Ecole Polytechnique de Montréal, we have developed effective monolithic fully coupled algorithms for generic FSI with flexible structures for 3D unsteady configurations. Our work has generated sufficient interest that several companies have funded extensions of our research (Gaz Transport & Technigaz, Commissariat à l'Énergie Atomique, TOTAL SA).**The research we propose is a natural extension of our previous research on simulation of FSI. It will focus on fundamental formulation and computational issues (contact, spectral element method) for accurate and consistent finite element simulation of structures undergoing large displacements and deformations induced by the flow of incompressible fluids.**Our goal is to extend FSI formulations to tackle outstanding while typical challenges in the offshore industry: flow induced vibrations of offshore structures with very low (zero) mass ratios, in-line with the flow arrangements of risers and galloping of riser towers. The usual decoupled algorithms fail miserably on these problems. Also, the current trend to drill in ever deeper waters implies that riser lines carrying the oil from the ocean floor to the surface now span more than 2000 m which requires that new buoyancy devices and new riser concepts be designed. Risers, buoys and riser towers dynamical behaviors result from strong Flow Induced Vibrations that are poorly handled by traditional loosely coupled algorithms. We believe that our fully coupled approach can overcome many of the difficulties presented by these new extreme FSI. **To achieve our goal we have identified the following objectives:**1. REFINE our fully coupled monolithic computational method to improve its accuracy and computational efficiency. We will extend our FE Formulation to isoparametric, higher order spectral elements to improve spatial accuracy and benefit from their higher computational efficiency by combining time-step and mesh adaptation strategies. This constitutes a natural extension of our methodology.**2. IMPLEMENT contact algorithms for rigid-body dynamics that will preserve our high-order temporal accuracy method. We favor using Lagrange multipliers for inequalities since they are free from approximations introduced by penalty methods for instance.**3. APPLY the formulation to problems with very low mass ratios that are relevant to offshore applications. Validation through experimental collaborative work between the low Reynolds number chanel of the Laboratoire de Mécanique des Fluides and Fluid-Structure Interaction Laboratory of the École Polytechnique de Montréal. We have identified the following problems of practical relevance:**a. Riser tower torsional and translational galloping,*b. Behavior of buoyancy can,*c. Riser assemblies converging to an offshore platform,**This generic research is innovative, as it will lead to the development and validation of computational models to shed insight into flow--induced vibration problems typical to offshore mechanics. The focus on low mass ratio constitutes a real added value since it is an identified weakness of present CFD/CSD softwares. Our work is motivated by the need to develop the tools required by the industry to operate safely future oil offshore field developments in Canadian ultra-deep waters. Our approach offers excellent perspectives of success because it is a natural extension of existing engineering design procedures.

流固耦合(FSI)是许多工程系统设计的关键。从适航性到飞机操纵性，几乎所有的机械系统都涉及到结构和流体流动之间的一定程度的耦合。在蒙特雷亚尔理工学院，我们开发了适用于具有柔性结构的通用FSI的有效的单片全耦合算法，用于3D非定常构型。我们的工作已经引起了足够的兴趣，以至于有几家公司资助了我们研究的扩展(Gaz Transport&Technigaz，CommissariaryàL的艾纳基原子公司，TOTAL SA)。**我们提出的研究是我们之前对FSI模拟研究的自然延伸。它将专注于基本的公式和计算问题(接触、谱元素方法)，以准确和一致地对结构进行由不可压缩流体流动引起的大位移和变形的有限元模拟。**我们的目标是扩展FSI公式，以解决近海行业中突出而典型的挑战：极低(零)质量比的海上结构的流动诱导振动，与立管的流动安排和立管塔架的舞动保持一致。通常的去耦合算法在这些问题上失败得很惨。此外，目前在越来越深的水域钻探的趋势意味着，将石油从海底输送到水面的立管现在跨度超过2000米，这要求设计新的浮力装置和新的立管概念。立管、浮标和立管塔架的动力行为是由强流致振动引起的，而传统的松散耦合算法处理能力较差。我们相信，我们的完全耦合方法可以克服这些新的极端FSI带来的许多困难。**为了实现我们的目标，我们确定了以下目标：**1.完善我们的全耦合整体计算方法，以提高其精度和计算效率。我们将把我们的有限元公式扩展到等参高阶谱元素，以提高空间精度，并通过结合时间步长和网格自适应策略来受益于它们更高的计算效率。这是我们方法的自然延伸。**2.为刚体动力学实现接触算法，这将保持我们的高阶时间精度方法。我们赞成使用拉格朗日乘子来处理不等式，因为它们不受惩罚方法引入的近似的影响。**3.将该公式应用于与离岸应用相关的质量比非常低的问题。通过Mécanique流体实验室的低雷诺数Chanel和蒙特雷亚尔理工学院流体-结构相互作用实验室之间的实验协作工作进行验证。我们已经确定了以下具有实际意义的问题：**a.立管塔架扭转和平移驰振，*b.浮力行为，*c.立管组件汇聚到海上平台，**这项一般性研究具有创新性，因为它将导致开发和验证计算模型，以深入了解海洋力学中典型的流致振动问题。对低质量比的关注构成了真正的附加值，因为这是目前CFD/CSD软件公认的弱点。我们工作的动机是需要开发该行业所需的工具，以便在加拿大超深水域未来的海上油田开发项目中安全运营。我们的方法提供了极好的成功前景，因为它是现有工程设计程序的自然延伸。