Experimental laboratory waves with a plunger-type wavemaker in waves-against-flow conditions

In this paper, a series of experiments was conducted to further expand the experimental benchmark of tests for plunger-type wavemakers in a laboratory water channel. The tests focus on the generation of waves in waves-against-flow conditions to study the impact of flow relative to the theoretical model given by the Plunger-Type with Flow (PTF) model and the Equal Volume with Flow (EVF) model. Both regular waves and irregular waves were studied for a range of mean flows through the channel and the accuracy of the theoretical wave parameters are quantitatively assessed. For regular waves, it was found that the EVF model is generally more accurate than the PTF model, especially under flow conditions. Additionally, wedges with a larger inner angle are less effective for wave generation, particularly for lower flows. For irregular waves, less errors in significant wave height were observed in the waves-against-flow conditions compared to waves-with-flow conditions, while the dominant wave frequencies were preserved in both conditions. By separating the incident spectra from that of the reflected one, a previously proposed correction for the PTF model was also addressed, validating its experimental applicability across a range of irregular spectra and flow conditions. • Plunger system in waves-against-flow conditions was experimentally explored. • Three triangular wedges and two analytical models were analyzed for regular waves. • The effect of mean flow and wedge angle on expected wave amplitude was studied. • Performance of a single wedge was studied for generating irregular wave spectra. • Model correction was validated for irregular waves in waves-against-flow conditions.