This paper presents a high fidelity CFD (Computational Fluid Dynamics) model for numerical prediction of the hydrodynamic forces on a self-reacting point absorber Wave Energy Converter (WEC). The component geometries are enclosed in two different fluid domains, each subjected to relative motion using a dynamic mesh algorithm. The transfer of field variables across the domains is achieved through an Arbitrary Mesh Interface (AMI). This unique methodology avoids cell deformation close to the component parts of the WEC, thus eliminating the errors in force calculation due to deformed cells. The continuity and momentum equations along with the free surface Volume of Fluid (VoF) method are solved separately in each domain. The validation of radiation force calculated from CFD is done by the experimental results for different heave oscillations test conditions.