Pile breakwater consists of a number of piles spaced closely. It works similar to the offshore breakwater by attenuating the energy of the waves and it is due to the turbulence caused because of wave-pile interaction. The efficiency of the pile breakwater of a single row and a double rows is investigated numerically. An open source Computational Fluid Dynamics (CFD) software REEF3D is used in the present study. Initially, the grid convergence study is conducted in a rectangular wave flume with a two-dimensional setup and the results are evaluated by comparing the numerical wave profile with the theoretical profile in accordance with the adopted wave theory. The efficiency of the numerically modeled pile breakwater is investigated in terms of the transmission coefficient. The simulations carried out are in accordance with the physical model studies as reported by Subba Rao et al., (1999). The numerically obtained results are validated with the experimental data. The numerically obtained results for the pile breakwater has shown an average of 91.5% agreement with that of experimental results.