A new method for simulating a frequency independent absorption within DHI's Mike 21 Boussinesq wave (BW) model is presented. This provides an increase in the accuracy of the simulation of wave processes around a hypothetical WEC array. Multiple monochromatic wave simulations are combined to represent a wave spectrum. Wave device characteristics are then simulated using porosity layers. A frequency dependent porosity for each device is then applied based on data taken from an experimental study. This method is tested for nearshore shallow water devices where the wave energy disturbance is quantified for flat and varying domain gradients.