A CFD analysis of the wave field in front of a U-OWC breakwater

The U-OWC is a port breakwater embodying an OWC with a small opening. Under wave action, the pressure acting on the outer opening of the vertical duct fluctuates, producing a pulsating water discharge. The interaction between incoming waves and the pulsating water discharge alters the wave motion in front of the breakwater wall. In this work, to investigate the wave field in front of the absorber breakwater, we carried out an experiment in a numerical wave flume. The water-air interaction is taken into account by means of the Volume-Of-Fluid (VOF) model implemented in the commercial CFD code Ansys Fluent. Both air and water flow fields are assumed to be unsteady and are computed solving the Navier-Stokes equations. The wave flume has been accurately tested on comparing numerical results vs standing wave field. It is found that in front of a U-OWC breakwater, nodes tend to disappear, as a consequence of energy absorption by the plant. The plant confirms its capacity to absorb a considerable share of the incident wave energy, even working far from resonance.