Numerical investigation of the wave resonance and absorption inside side channels

Wave resonance and absorption are typical phenomena in marine or coastal structures. This paper numerically describes the resonant absorption of water waves in a wave tank with two closely spaced resonant side channels mounted. Regular waves are produced on one end of the wave tank based on the momentum source function. The resonant modes around the symmetric and asymmetric channels are extracted and analyzed. Seven monitoring points near the channels are selected to study wave transmission and surface elevation characteristics. The first-order mode accounts for most of the wave energy and basically displays the energy distribution and wave transmission process. For resonant absorption, the channels pump water from the crest to the trough of the passing wave sequentially and periodically, during which wave energy is extracted and sustained in the channels; therefore, the amplitude of surface elevation in the channels increases sharply, which in turn promotes the loss of wave energy.