2008.74: OCEAN CURRENT PREDICTION IN TOWED CABLE HYDRODYNAMICS UNDER DYNAMIC STEERING
2008.74: N Polydorides, E Storteig and W.R.B. Lionheart (2008) OCEAN CURRENT PREDICTION IN TOWED CABLE HYDRODYNAMICS UNDER DYNAMIC STEERING.
Full text available as:
|PDF - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader|
This paper considers the problem of reconstructing the velocities of o cean currents impinging on a towed streamer cable sparsely equipped with steerin g elements. The study is based on a two-dimensional model describing the quasi-s teady motion of the towed cable in the presence of hydrodynamic drag and steerin g forces that depend nonlinearly on the angle of attack. To derive the proposed methodology we ﬁrstly outline the hydrodynamic equations used in solving the for ward problem by which the cable’s velocity, curvature and tension are obtained i n the knowledge of the towing vessel’s motion, the ocean current velocities and the drag coeﬃcient characteristics of the steering elements. In sequence we form ulate the inverse problem of inferring the ocean velocities using a ﬁnite set of noise-infused positioning and tension measurements showing that this is nonline ar and ill-posed. To solve the inverse problem we adopt Newton’s scheme for nonl inear convex problems in conjunction with generalized Tikhonov regularization. T he problem under consideration bares signiﬁcant diﬀerences from the linear non-s teered formulation addressed in (12), due to the nonlinearity in the forward met hod as well as the discontinuities observed in the forward measurements due to t he steering forces. A series of numerical simulation studies is subsequently pre sented in order to demonstrate the practical performance of the proposed techniq ue in reconstructing the ocean currents velocity proﬁle and angle of attack.
|Item Type:||MIMS Preprint|
Accepted for Inverse Problems in Science and Engineering
|Uncontrolled Keywords:||ocean current prediction, towed seismic array, inverse problem|
|Subjects:||MSC 2000 > 34 Ordinary differential equations|
MSC 2000 > 65 Numerical analysis
MSC 2000 > 76 Fluid mechanics
|Deposited By:||Prof WRB Lionheart|
|Deposited On:||15 July 2008|