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首页> 外文学位 >Gravity current-submarine structure interaction: Hazard analysis via high-resolution simulations.
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Gravity current-submarine structure interaction: Hazard analysis via high-resolution simulations.

机译：重力-海底结构相互作用：通过高分辨率模拟进行危害分析。

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摘要

As the offshore industry moves towards deeper ocean environments, submarine structures become increasingly exposed to less understood hazards, among them gravity and turbidity currents. With this motivation in mind, the interaction of gravity currents with submerged cylinders mounted at or above a non-erodible bed is investigated by means of Navier-Stokes simulations. To the author's knowledge, the present is the first in-depth numerical study of such interaction. Emphasis is placed on the drag and lift forces exerted on the cylinder, the wall shear stress near the cylinder, and the reduction of the front speed of the oncoming gravity current.;The drag increases towards a maximum when the current impacts the cylinder, and eventually reaches a mean quasisteady value. Maximum loads are crucial information for the design of submarine structures. Thus, an estimate is obtained for the maximum drag, by noticing that this drag results from an imbalance of hydrostatic pressure forces, and the deceleration of dense fluid flow as it encounters the cylinder. Some time after the current meets the cylinder, the drag and lift undergo sustained fluctuations for certain parameters. These fluctuations result from Karman vortex shedding. The wall shear stress near the cylinder is related to the scour near pipelines mounted on erodible beds. The magnitude of the wall shear stress is largest when the current impacts the cylinder. Consequently, the most aggressive scour is expected at impact. This is the key difference between the scour in gravity current flows and constant density flows. The reduction of the front speed of the oncoming gravity current by protective barriers is predicted with a simplified theoretical model, based on the shallow water equations.
机译：随着近海工业向更深的海洋环境发展，海底结构越来越暴露于人们所不了解的危险之中，其中包括重力流和浊流。考虑到这一动机，通过Navier-Stokes模拟研究了重力流与安装在非侵蚀性床层或上方的水下圆柱体的相互作用。据作者所知，目前是这种相互作用的首次深入数值研究。重点放在施加在圆柱体上的阻力和提升力，圆柱体附近的壁面剪切应力以及即将到来的重力流的前端速度的降低;当电流冲击圆柱体时，阻力朝最大方向增加，并且最终达到平均准稳态值。最大载荷是设计海底结构的关键信息。因此，通过注意到这种阻力是由于静水压力的不平衡以及致密流体流在遇到圆柱体时的减速引起的，从而获得了最大阻力的估计值。电流到达圆柱体后的一段时间，对于某些参数，阻力和升力会持续波动。这些波动是由卡曼涡旋脱落引起的。圆柱附近的壁面剪切应力与安装在易蚀层上的管道附近的冲刷有关。当电流冲击圆柱时，壁切应力的大小最大。因此，预计最激进的冲撞会产生影响。这是重力流冲刷和恒定密度冲刷之间的关键区别。通过简化的理论模型，基于浅水方程，可以预测到保护栅栏将迎面而来的重力流的速度降低。

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  • 作者

    Gonzalez, Esteban.;

  • 作者单位

    University of California, Santa Barbara.;

  • 授予单位 University of California, Santa Barbara.;
  • 学科 Engineering Marine and Ocean.;Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 187 p.
  • 总页数 187
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 海洋工程;机械、仪表工业;
  • 关键词

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