ACA/BEM for solving large-scale cathodic protection problems

Abstract

Cathodic protection (CP) techniques are widely used to avoid corrosion sequences in offshore structures. Boundary Element Method (BEM) is an ideal method for solving such problems since it requires only the meshing of the boundary and not the whole domain of the electrolyte as Finite Element Method does. This advantage becomes more pronounced in CP systems where electrochemical reactions occur mainly on the surface of the metallic structure. In the present work, an accelerated BEM enhanced by Hierarchical Matrices and Adaptive Cross Approximation techniques (ACA) is proposed for the solution of large-scale 3-D CP problems. An offshore oil steel platform, galvanically protected by a number of aluminum sacrificial anodes, is analyzed by means of the proposed ACA/BEM. The nonlinear polarization curves for steel and aluminum in seawater are employed to facilitate the boundary conditions. The potential, as well as, the current density are effectively evaluated and presented.