This study, deals with the investigation of the accuracy and performance of a novel method for simulation of oscillating wave surge converter (OWSC). The OWSC is an instrument with one degree freedom mounted in near shore areas which oscillates back and forth. This device is used to harvest sea wave energy. The developed model is based on the well-known volume of fluid (VOF) method. Due to the nature of the OWSC motion, the VOF method in conjunction with unstructured dynamical grid mesh has been used in the literature. But in this study, a structured grid mesh is employed which facilitates the numerical preparation and the speed of simulation process. The results are compared with the experimental data and the results of numerical method in the literature by dynamical grid mesh. This comparison shows the high accuracy of the developed model in this study. The model validation is performed in an extreme condition with steep waves which need an accurate numerical scheme. The external forces including power take off (PTO) forces are also simulated. The capture factor, energy absorption condition and the effect of PTO on angle, angular velocity and slamming of the OWSC are also investigated. Finally, the effect of wave height and the PTO stiffness on the capture factor and absorbed energy by the OWSC for waves with a specific period are investigated.