A statement to conference attendees:
An innovative numerical approach for ship-wave generation, propagation and interaction with inner harbor basins (agitation) is presented. This new tool will help harbour managers to early assess and manage ship speeds, trajectories and possible impacts/ affections related with their downtime analysis.
INTRODUCTION
The present study describes the set of works related with the numerical evaluation of waves generated by passing ships within the harbor. Ship-waves (or wake waves), are generated by the disturbance of the moving vessel, which delivers a set of oscillations that may interrupt or interfere the safe-mooring activities.
Since the energy, form and frequency of ship-waves depends on: speed, accelerations, track and geometry of the vessel; overall bathymetric contours; and wharf/ pier/ quay geometries, it is necessary to design a reliable tool that integrates all these characteristics.
Activities such (safe) loading and unloading of materials or passengers, navigation and sedimentary dynamics adjacent to harbour infrastructures (silting), are closely related with ship-wave generation and propagation.
Thus, the present study presents a numerical alternative to characterize this new type of forcing, with the aim to provide a new diagnosis system for any harbour manager. This innovative tool will provide a decision tool based on a realistic harbour agitation model, forced by a ship travelling inside real basins and harbors’ domains, for any vessel/ operator/ route/ navigation protocol/ speed, etc.
Harbour managers will be able to evaluate the agitation effects, know and limit ship speeds, change routes, manage hours, and even change the ship geometries and sizes, in order to satisfy the Port Authority safety limits and to improve the downtime records.
METHODOLOGY
The methodology deals with the modification of a wave propagation numerical model, based on the non-linear and dispersive Boussinesq equations, by including the effect of the passing ship and the subsequent flow perturbation, propagation, and interaction with bathymetries docks AND basins.
The numerical strategy requires the establishment of a complete working methodology: pre-processing and adaptation of the bathymetric, port and AIS data (ship Automatic Identification System), in order to provide an easy-to-use, relocable and reliable tool ready to be applied in any real harbor at any stage: pre-design, design, construction, operation and modification (extension, improvement, etc.).
Hence the following tasks were developed:
- A state-of-the-art review related with the mathematical and numerical generation of the waves generated by passing ships, in order to identify the best strategy that suits the numerical needs.
- Adaptation of the numerical tool to be used for a good ship-wave generation, taking into account the most relevant physical characteristics of the ship (speeds and geometries), as well as the spatial trajectories physics. This task involves an exhaustive validation process of the numerical tool using benchmark laboratory tests and field data.
- A detailed guideline to numerically assimilate the ship routes, sizes and speeds for an extensive catalogue of ships for any Port Authority is presented, based on realistic AIS databases. This catalogue is used in the following tasks.
- Run of the catalogue of ships with the numerical tool (once modified, adapted and validated), in order to obtain the corresponding characteristics of the ship-waves (individual wave heights and associated oscillation periods), at different pre-established control points and ship maneuvering areas.
RESULTS
As an example, the numerical tool/system is adapted and validated (with in situ measurements) in Algeciras Port in Spain, based on 2-year AIS database, including the numerical propagation of 40 different ship tracks. The system is actually integrated into Algeciras Port met-ocean strategy.