Dynamics and Hydrodynamics of Ship in Approaching Fairways (CONFINED WATERS)

Duration: 01.03.2008-28.02.2011 (36 months)

Coordination: Instituto Superior Técnico

Funding Entity: Portuguese Foundation for Science and Technology

The Project aims at the development of a mathematical model discribing the manoeuvring of ships in shallow water of variable depth, which occur often in port approaches. The main practical problem addressed is to identify which is the required depth of the approach channels so that the entering ship doesn´t hit the botton and doesn´t hit the botton and doesn´t lose its manoeuvring capabilities due to bottom effects. Solution of this problem will allow better planning of the required dredging operations and will allow port authorities to establish the larguest size of ships that can use safety the approach fairways. This problem is naturally split into the hydrodynamic problem of estimating the interaction forces acting between the ship´s hull and all the rigid boundaries which includes hulls of other ships sailing in close proximity to the ship in concern and the bottom which is not necessarily flat and horizontal. Due to the complicated geometry, the study will be based on the hierarchy of three hydrodynamic models of different complexity and accuracy. The first model will be based on the finite volume CFD code solving the Reynolds-Averaged Navier-Stokes Equations (RANSE) recently development at the department . This code is expected to produce the most accurate results as is modelling the real fluid with the nonlinear free-surface conditions but is slow and requires a cluster of computers to be used effectively. Results obtained with the RANSE code will be mainly used for validating results obtained with simpler approaches. The second hydrodynamic model is based on the potential flow panel code which has been also recently implementef at the Unit. This methods neglects all viscosity and free-surface effects but accounts fully for the 3D character of the flow. This method is much faster then the RANSE solver but likely not fast enough for efficient online calculations. The third model exploits the ship hull´s slenderness and will be based on the strip theory matched to semi-empiric models for the hull hydrodynami forces in deep water. The development of this model will benefit from the algorithm and code capable to compute the hydrodynamic characteristics of the ship sections recently development by the applicants. This code implements the boundary-integral-equation method and dealt primarily with the deep water condition bur has been recently extended to the case of arbitrary bottom. As the strip method neglects 3D effects it will be validated against the 3D panel code and the errors will be estimated. However, these, these errors are expected to be acceptable and as the strip method is the fastest, it is expected to be the prederred option in real-time manoeuvring simulations.

Project Team

Associated Publications