Experimental study on the hydrodynamic performance of an oscillating water column with frontal plates

The efficiency of wave energy devices can be enhanced by positioning them at pre-defined locations of concentration of the energy flux which could be either by nature or through man-made methods. In shallow waters, energy flux density remains nearly uniform throughout the depth, while in intermediate and deep waters, it varies along with the depth with more energy being transferred nearer to the free surface. In the present study, a horizontal plate is used to concentrate the wave energy within a limited depth from the surface by inducing the waves to shoal. The plate length required for efficient shoaling is experimentally studied. An Oscillating water column, a proven wave energy extraction device, is fixed over the plate and its hydrodynamic efficiency is evaluated. The optimal distance between the leading edge of the plate and OWC is found. Through this method, it is observed that the hydrodynamic efficiency of OWC increases by about 10% compared to in the absence of the plate. •Frontal plates concept to a Oscillating water Coloumn (OWC) to harvest wave energy is introduced.•The plate length required for better wave amplification is experimentally studied and a predictor equation is arrived.•The plate of half the wave length is suggested for better wave amplification by shoaling.•The physics behind the dimensional requirement of the plate is detailly explained.•The hydrodynamic efficiency of OWC increase by 10% due to presence of plates.