Quality of regular waves experimentally generated by plunger-type wavemakers with mean flow

This paper experimentally studies the quality of regular waves generated by a plunger-type wavemaker with a triangular wedge, as analyses on wave quality in such systems remain limited and often lack quantitative assessment. Three wedge geometries with inner angles of 25.7°, 35.0°, and 45.0° were tested under both no-flow and flow conditions. Wave quality was evaluated based on metrics of wave amplitude, vertical symmetry, and horizontal symmetry. With respect to wave amplitude, two leading analytical models were compared: the Equal Volume with Flow (EVF) model based on mass conservation and the Plunger-Type with Flow (PTF) model based on potential flow theory. After an operational correction to both models, the analysis showed that the PTF model was more accurate on average, but the EVF model provided comparable results. Among the tested configurations, the wedge with a 35.0° angle consistently generated waves with higher quality in terms of amplitude prediction and symmetry across varying flow conditions. These findings suggest that the use of an intermediate angled wedge offers a practical and reliable approach to generate linear waves in laboratory experiments. It is recommended that future studies with a plunger-type wavemaker adopt a similar geometry to enhance experimental accuracy in the presence of flow. • The quality of waves produced by a plunger system was experimentally quantified. • Regular wave amplitude, vertical symmetry, and horizontal symmetry was analysed. • A comparison between analytical plunger-type wavemaker models was conducted. • The effect of wedge angle was studied through experimental measurements. • The impact of waves-with-flow conditions on wave quality were explored.