A vertical porous or perforated structure can be considered an effective breakwater due to its efficient use in deep water when compared to conventional breakwaters. The hydrodynamic performance of this breakwater can be evaluated by studying the wave reflection and transmission through it. Various experimental studies in the past have shown the performance characteristics of this structure, but their application is limited due to the required effort, time, and manpower (Rajendra et al., 2017). As an alternative, a numerical model can be advantageous in representing exact situations and providing additional benefits. Therefore, as a preliminary study, the wave reflection and transmission of the vertical perforated breakwater are simulated in a numerical wave tank using a unique approach to defining porous boundary conditions. The numerical wave tank is developed using a finite volume-based FLUNET tool with a viscous-laminar model configuration. However, the porous boundary condition is defined in terms of the inertial resistance coefficient, which was derived from pressure drop measurements taken across the perforated structure during lab experiments. The wave reflection and transmission obtained from the numerical wave tank show good agreement with the experimental data. Interestingly, a closer examination of the flow field in the vicinity of the breakwater indicates partial standing wave formation, which contributes to an increase in wave reflection for a limited case.