Damage to the Mutriku OWC breakwater – some lessons from further analysis

In a bold experiment, the Basque government constructed an innovative Oscillating Water Column (OWC) power station breakwater outside the small fishing port of Mutriku during 2007-2008. While the main structure was a rubble mound, the OWC section of the breakwater consisted of 16 chambered vertical wall units formed by stacked concrete layers. Before the power station could be completed however, storms hit the breakwater in December 2007 and March 2008). A further storm in January 2009 result in severe structural damage to a number of the OWC cells. Previous papers have explained some of the contributions to damage, but have not described detailed flows, loads and consequent responses. In order to understand the causes of the damage, this paper will describe recent numerical model (CFD) experiments to calculate flows, pressures and resulting loads at critical positions within the OWC cells.