Abstract: Three-wave resonant
interactions constitute an essential nonlinear mechanism
coupling capillary surface waves. In a previous work, Haudin et al. [Phys. Rev E 93,
043110 (2016)], we have characterized experimentally the
generation by this mechanism of a daughter wave, whose amplitude
saturates due to the viscous dissipation. Here, we show
experimentally the generation of a daughter wave verifying the
resonant conditions, but not the dispersion relation. By
modeling the response of the free surface at the lowest
nonlinear order, we explain this observation as a forced
interaction. The observation of free surface excitations not
following the linear dispersion relation then becomes possible.
This forced three-wave interaction mechanism could have
important consequences for wave turbulence in experimental or
natural systems with non negligible dissipation.