## Theoretical Aspects

The boundary element method (BEM) has been proved to provide the optimum solution to problems associated with corrosion simulation [2]. The BEM requires the user to only describe the boundary or surface of the ship to be modelled thus simplifying the modelling process. There are also additional benefits which are described in [2]. Figure 1 shows an example of a BEM model.

To model a CP problem the computer model must simulate the IR drop through the electrolyte and the electrochemical electrode kinetics on the metallic surfaces. Therefore, a boat in the sea can be considered as a galvanic systems (Figure 2).

BEM solution of the Laplacian in the sea water, combined with representation of the electrode kinetics associated with different surface types, has been shown to provide accurate results for the complex current fields in the sea water and hence the Underwater Electrical Potential or UEP signature. The CRM signature generated by the currents flowing in the sea water can be found by solving the vector potential.

Control of the complete sequence of steps is simplified by use of a "wizard" which allows the user to very easily perform all operations. If all steps are to be performed the user actions simply involve selection of the data file and assignment of magnetics properties. The solution sequence is then triggered and proceeds fully automatically.

**See also:** Boundary element modeling,Corrosion models, Knowledge based models, Mechanistic models, Pitting fatigue models, Risk based models

*Predicting corrosion related electrical and magnetic fields using BEM*, Robert Adey and John Baynham, BEASY