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Numerical prediction of the hydrodynamic loads and motions of offshore structures.

机译：海上结构的水动力载荷和运动的数值预测。

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摘要

A generalized numerical method for solution of the incompressible Navier-Stokes equations for two- and three-dimensional geometries has been developed. Incompressible fluids are encountered in a variety of engineering problems including offshore marine sciences, low-speed aerodynamics, and a wide class of civil and industrial engineering applications. The focus of the research is rooted in offshore hydrodynamics with the study of how incompressible fluids interact with the structures they surround, and in turn, how these structures respond to the external fluid forces. One important instance of this flow-structure coupling arises with the prediction and suppression of vortex-induced vibrations (VIV) which is a critical concern to the offshore oil industry, particularly with the design of offshore risers and spars. Although typical amplitudes of vibration for risers undergoing VIV are small, the risers can still experience fatigue failure as a result of the persistent dynamic stresses. Most all of the current models used to predict VIV response characteristics are derived from a database of experimental results with a large scatter of predicted responses being observed. However, surprisingly little work has been done to apply the governing incompressible Navier-Stokes equations to numerically obtain flow structure solutions about cylindrical members. Hence, the goal of this research is to develop and validate a tractable numerical option for approaching VIV and other offshore hydrodynamic problems.; In terms of numerics, a pressure correction method is implemented for solution of the incompressible Navier-Stokes equations using deformable hybrid grids and an empirical turbulence model. An analytic wall function is combined with the turbulence model to increase solution efficiency and reduce the near-wall resolution required to model fully turbulent flows. The pressure correction method is loosely coupled with an elastic body structural response to obtain unsteady flow structure solutions, In addition, the entire flow-structure solution methodology has been combined with a feedback control mechanism to assess the possibility of using dynamic positioning to control certain classes of VIV motion. Solutions of the Navier-Stokes equations are obtained using an edge-based finite volume discretization on non-staggered grids and artificial dissipation is introduced into the momentum equations to suppress oscillatory solutions.
机译：提出了一种求解二维和三维几何不可压缩Navier-Stokes方程的通用数值方法。不可压缩流体在各种工程问题中遇到，包括海上海洋科学，低速空气动力学以及广泛的土木和工业工程应用。该研究的重点在于海上流体力学，该技术研究不可压缩流体如何与其周围的结构相互作用，进而研究这些结构如何响应外部流体力。这种流动-结构耦合的一个重要实例出现在涡流诱发振动（VIV）的预测和抑制中，这是近海石油工业尤其是近海立管和翼梁的设计所关注的关键问题。尽管经受VIV的立管的典型振动幅度很小，但由于持续的动态应力，立管仍会遭受疲劳破坏。当前用于预测VIV响应特征的大多数模型都是从实验结果数据库中获得的，观察到的预测响应有很大的分散性。然而，出乎意料的是，很少有工作可以应用控制性不可压缩的Navier-Stokes方程来数值获得有关圆柱构件的流动结构解。因此，本研究的目的是开发和验证用于解决VIV和其他海上流体动力学问题的易处理的数值选择。在数值上，采用可变形混合网格和经验湍流模型对不可压缩的Navier-Stokes方程进行压力校正。解析壁函数与湍流模型相结合，可提高求解效率并降低为完全湍流建模所需的近壁分辨率。压力校正方法与弹性体结构响应松散耦合以获得不稳定的流动结构解决方案。此外，整个流动结构解决方案方法已与反馈控制机制相结合，以评估使用动态定位来控制某些类别的可能性VIV运动。 Navier-Stokes方程的解是在非交错网格上使用基于边的有限体积离散化获得的，并且将人工耗散引入了动量方程中以抑制振荡解。

著录项

  • 作者

    Schulz, Karl Wayne.;

  • 作者单位

    The University of Texas at Austin.;

  • 授予单位 The University of Texas at Austin.;
  • 学科 Engineering Marine and Ocean.
  • 学位 Ph.D.
  • 年度 1999
  • 页码 211 p.
  • 总页数 211
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 海洋工程;
  • 关键词

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