Ocean current prediction in towed cable hydrodynamics under dynamic steering
Ocean current prediction in towed cable hydrodynamics under dynamic steering
复制标题
动态转向下拖缆流体动力学海流预测
DOI：
10.1080/17415970802390010
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发表时间：
2009
影响因子：
1.3
通讯作者：
W. Lionheart
中科院分区：
文献类型：
--
作者：
N. Polydorides;Eskild Storteig;W. Lionheart
本文考虑的问题，重建的速度的海流冲击拖缆稀疏配备转向元件（SE）。该研究是基于一个二维模型，描述的准稳态运动的拖缆中存在的水动力阻力和转向力，非线性地依赖于攻角。为了推导出所提出的方法，我们首先概述了用于求解正问题的流体动力学方程，通过该方程，在拖船的运动、海流速度和SE的阻力系数特性的知识中获得缆线的速度、曲率和张力。在序列中，我们制定的逆问题推断海洋速度使用有限的一组噪声注入定位和张力测量表明，这是非线性和不适定的。为了解决反问题，我们采用牛顿的计划结合广义Tikhonov正则化的非线性凸问题。所考虑的问题与（N. Polydorides，E. Storteig和W. Lionheart，2007，Forward and inverse problems in towed cable hydrodynamics，Ocean Engineering 35（2008）），这是由于前向方法中的非线性以及由于转向力在前向测量中观察到的不连续性。随后进行了一系列数值模拟研究，以证明所提出的技术在重建洋流速度剖面和攻角方面的实际性能。
This article considers the problem of reconstructing the velocities of ocean currents impinging on a towed streamer cable sparsely equipped with steering elements (SE). The study is based on a two-dimensional model describing the quasi-steady motion of the towed cable in the presence of hydrodynamic drag and steering forces that depend nonlinearly on the angle of attack. To derive the proposed methodology we first outline the hydrodynamic equations used in solving the forward problem by which the cable's velocity, curvature and tension are obtained in the knowledge of the towing vessel's motion, the ocean current velocities and the drag coefficient characteristics of the SE. In sequence, we formulate the inverse problem of inferring the ocean velocities using a finite set of noise-infused positioning and tension measurements showing that this is nonlinear and ill-posed. To solve the inverse problem we adopt Newton's scheme for nonlinear convex problems in conjunction with generalized Tikhonov regularization. The problem under consideration bares significant differences from the linear non-steered formulation addressed in (N. Polydorides, E. Storteig and W. Lionheart, 2007, Forward and inverse problems in towed cable hydrodynamics, Ocean Engineering 35 (2008)), due to the nonlinearity in the forward method as well as the discontinuities observed in the forward measurements due to the steering forces. A series of numerical simulation studies is subsequently presented in order to demonstrate the practical performance of the proposed technique in reconstructing the ocean currents velocity profile and angle of attack.