Correct generation of the bound set-down for surface gravity wave groups in laboratory experiments of intermediate to shallow depth

Using linear (first-order) wave generation theory in laboratory experiments, leads to significant contamination of the field by free non-linear (second-order) error waves, increasingly so at shallower depths. Second-order has previously been established, and correct bound set-down, made up from second-order waves sub-harmonic part spectrum, for bichromatic irregular fields shallow intermediate depth. In present work, different previous studies, we validate explicitly isolated groups, which provide a demanding test on stroke length wavemaker. We do water depth, where some attempts full elimination have hampered limited paddle stroke. overcome these limitations applying wavemaker piston-type with an extended that can thence generate set-down correctly. show are eliminated considering groups relative depths k0d = 0.6–1.1, important applications coastal engineering such as run-up overtopping.