KEYWORDS: Curved front, Pile-supported breakwater, Wave Reflection, Energy dissipation, OWC, Hydrodynamic efficiency, Wave induced pressures and Run-up Due to an increase in the maritime trade and an associated increase in vessel sizes, breakwaters are sought in water depths of more than 20 m for berthing of large vessels. Though rubble mound breakwaters are quite effective in wave energy
dissipation, they are unfeasible for such large water depths as they leave a large footprint on the ocean floor. While floating units are suitable for deep waters, they are not so stable under harsh environmental conditions. Fixed pile-supported breakwaters are quite effective in withstanding the forces due to waves and in providing the
required harbor tranquility. The wave energy transmission past pile-supported breakwaters is less particularly under deep-water conditions wherein the incident wave energy is concentrated near the free surface. However, a reduction in wave energy reflection is also desirable to facilitate the navigation of vessels on the seaside. It is observed from the different configurations of pile-supported breakwaters that a curved front or a porous barrier on the seaside experiences less reflection.
Interestingly, the curved front breakwater models investigated to date are of convex shape on the seaside. While concave profiles have been adopted as seawalls earlier, their application as pile-supported breakwaters is scarce. Thus, an experimental investigation is carried out to assess the hydrodynamic characteristics of two different
concave profiles viz. Galveston seawall (GS) shape and circular cum parabola shape (CPS) adopted as the front face of pile-supported breakwaters designated as GS-PSB and CPS-PSB respectively. The breakwater models are subjected to the action of regular and random waves in a wave flume covering intermediate to deep-water
conditions. The parameters investigated in the experiments are wave transmission, reflection, energy dissipation, wave-induced pressures, and run-up. A qualitative assessment of overtopping is also reported in the study.

Comparison is made with a vertical wall type pile-supported breakwater, VW-PSB. It is found that the wave energy transmission past GS-PSB and CPS-PSB is marginally less than VW-PSB in intermediate water depths and identical in deep-water condition. The GS-PSB due to its steeper slope serves like the VW-PSB with increased reflection. The wave reflection from CPS-PSB with a flat slope at lower elevation is however less than that of VW-PSB by 10% to 75%. The wave-induced
pressures and run-up over GS-PSB and CPS-PSB are found to be higher which can be reduced by integrating a wave screen on their seaside. Two types of wave screen are considered viz. the tubular wave screen made of circular pipe sections and the louver wave screen comprising of an array of plates inclined at 60 ̊ to horizontal. The porosity of the wave screen is fixed at 25% to achieve less reflection.The inclusion of a wave screen does not significantly alter the transmission characteristics of GS-PSB and CPS-PSB, but the wave reflection from GS-PSB is considerably reduced. The wave screen does not significantly improve the performance of CPS-PSB since it is as such less reflective and more dissipative. Experiments are also carried out to assess the performance of an oscillating water column (OWC) device having a curved entrance and mounted on piles (OWC-PSB).OWC-PSB is found to result in marginally less reflection than VW-PSB due to the
conversion of the incident wave energy into water column oscillation in the OWC chamber. The hydrodynamic efficiency of the OWC attains a maximum of 50% in deep-water condition.