Focusing of wave-induced flow through a submerged disk with a tubular opening

• Experimental and numerical study of the hydrodynamics of wave-focusing.
• The wave-induced flow through a submerged disk with a tubular opening is measured with a PIV laser.
• The linear potential theory is used for calculations.
• Experimental data and numerical predictions compared well with one another.
• The study validates aspects of an envisioned wave energy converter.

This study is on the vertical wave-induced velocity through an opening in a fixed, submerged and impervious horizontal disk, that is positioned near the free surface. Piercing this body is a tubular section, having an opening flush with the top surface and extending completely through the body. Experiments are conducted in a wave flume, where monochromatic waves propagate over the submerged surface of a free-standing disk model. Wave elevation is recorded using a capacitive-type wave gauge. The oscillating wave-induced flow through the submerged surface is measured by a particle image velocimetry (PIV) laser. Numerically, the flow within the opening of the submerged surface is modeled by use of the Green function method within the confines of linear potential theory. Both the experimental and numerical results of this phenomenon are compared. The outcome is pertinent to the development of a new wave energy converter.