A numerical model based on the Discrete Vortex Method has been developed for the analysis of flow separation along a maneuvering ship, which is represented by the slender body approximation representing the hull as a series of two-dimensional double-body sections. The boundary layer flow is modeled by a continuous layer of discrete vortices distributed over the contour of each hull section and convected into the free stream under the influence of the ambient flow. The vortex strength is chosen to satisfy the non-slip condition at each collocation point. The numerical model allows the study of separated flow around realistic ship hulls that do not have well-defined separation points. The vorticity transport equation is solved using a grid based method that incorporates a two-stage conformal transformation of the hull shape by means of a Laurent series. The effects of varying the drift angle and yaw rate on a ship's maneuvering characteristics are presented for the British Bombardier moving with both drift and turning motions. The results show, that the flow around a maneuvering ship can be useful modelled using slender body theory modified by the Discrete Vortex Method to account the hydrodynamic forces induced by trailing vortices. Although the presented method does not include all the fine details of the flow at the extreme stern, its agreement with experimental results is much better than that of the unmodified slender body model taking into account only the hydrodynamic masses and not the trailing vortices.
The estimation of the hydrodynamic forces acting on a manoeuvring ship using the Discrete Vortex Method
Berechnung der hydrodynamischen Kräfte auf ein manövrierendes Schiff mit der Methode der diskreten Wirbel
Ship Technology Research / Schiffstechnik ; 50 , 2 ; 66-76
2003
11 Seiten, 11 Bilder, 24 Quellen
Article (Journal)
English
Abreißen der Strömung , Drehmoment , Grenzschichtströmung , konforme Abbildung , Manövrierfähigkeit , Näherungsverfahren , numerische Strömungsberechnung , Schiffskörper , Seitenkraft , Singularitäten-Verfahren , Theorie-Experiment-Vergleich , Umströmung , Wirbelfluss , Wirbelströmung , zweidimensionale Strömung
Taylor & Francis Verlag | 2003
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