The objective of this thesis is to validate a wave simulation code. In order to achieve this,the displacements at the top of a monopile werecompared between a wave flume model and a finite element model.Initially,real waveconditions weremeasured in an offshorewind turbine in the North Sea.This data wasapplied to createaccurate waves in a wave flume at the DTU Mechanical Engineering Laboratory. In the flume, a scaled modelof a monopile was positioned and the displacements at the top sampled. After processing the data with MATLAB and applying the Operational Modal Analysis, it was possible to obtain the modal properties of the model, such as mode shapes, natural frequencies and damping ratios.A finite element modelwas developed with ANSYS, which accurately recreated the wave flume and was updated to have identical modal properties. The wave simulation code was applied to this finite element model and the displacementsat the top were compared with those from the wave flume model