Can Triadic Resonance Instability be ignited by the interaction between an internal wave field and a vortex ring?

The role played by Triadic Resonance Instability (TRI) in transferring energy across the wavenumber and frequency spectra for internal waves is becoming increasingly recognised. However, much of the experimental work to date has considered the development of this crucial mechanism in the idealised conditions of monochromatic plane waves or wave beams. Here we present novel experimental results exploring whether TRI can be ignited in a pre-existing wave beam by the passage of a vortex ring. In this study, the internal wave field is generated from the motion of a flexible horizontal boundary condition, driven by an array of independently controlled actuators. This allows for varying amplitude, frequency and wavelength in both the spatial and temporal domain. We therefore examine the effect of varying the wave input parameters on the generation of this instability and determine if, under certain conditions, the presence of the vortex ring can ignite the TRI.