Fast and accurate numerical modelling of wave energy converters (WECs) is critical to cost effective development of these technologies. With the assistance of Applied Renewables Research Ltd, Bombora Wave Power has developed a linear numerical performance modelling suite for their flexible membrane WEC (mWave). For the purpose of the numerical model validation, tank testing of a 1:15 scale physical model of this device was conducted at the Australian Maritime College. The numerical model predictions were compared against measured data for 115 monochromatic wave tank-tests. The expected linearity of test waves was estimated by the Ursell parameter. For non-linear waves, phase-averaged time series data was found to agree very well with model pressure and flow predictions. The numerical model also provides a good indication of performance for highly non-linear waves across a broad range of water depths, wave frequencies and heights.