Continuous Flooding

Due to a number of high profile disasters involving Ro-Ro ferries in recent years, there has been an increased interest in modelling continuous flooding within marine vessels. For many years safety regulations for marine vessels have be prescriptive in nature rather than being based upon the analysis of an individual vessel. This is now changing and, within the regulations laid down by the International Maritime organization, there is currently provision for vessels to comply with these regulations via a route of numerical equivalence. It is generally considered that in the future numerical equivalence will become the predominant method for the verification of ship safety. The Continuous Flooding module in Calc implements a method of modelling that is based on the numerical simulation of the physical properties of fluids and the geometry of the vessel, rather than some prescriptive approach. Fundamentally, what is to be modelled is the distribution of fluid within the compartments of a vessel and the attitude of that vessel to the water in which it is floating, as time evolves. In addition to the compartment and ship geometry, it is necessary to model any openings through which fluid may flow; both openings between compartments and openings in the hull, whether these openings are by design or due to the result of damage.

As presently implemented there are a number of limitations, as follows:

1. The vessel is not effected by wind and waves, that means, it does not roll or pitch.

2. The original contents of compartments cannot be changed during the simulation.

3. The simulation always starts from an intact loading condition, with no damage.

Some of these limitations will be removed in due course.

The procedure for carrying out a simulation is as follows:

4. Set up the initial loading condition, openings, pumps, using the Edit command.

5. Run the simulation as a normal calculation. The simulation may, however, be stopped using the red Abort Calculation button, without losing the results calculated up to that point.

6. Inspect and/or print the simulation report.

7. Activate the 3D view and play back the simulation. This is controlled by means of the Run flooding sequence, Stop animation, Go to first stage, Step back, Step forward, and Go to last stage buttons.

Continuous Flooding - Play back of flooding simulation in 3D view.