In this work the absorption of water waves in a numerical wave flume is discussed in terms of performance and robustness. A general formulation for the analysis of fluidstructure interaction problems using the Particle Finite Element Method (PFEM)1 is employed to simulate a numerical wave flume. The implementation of a wave dissipative zone changing the fluid viscosity properties is tested with the goal of absorbing waves reflected by a vertical wall. The accuracy of this method is analyzed testing a set of viscosity distribution inside the dissipative zone using a prototype scale numerical wave flume.