Measuring energy dissipation of reflecting internal waves using experiments and simulations

Lee et al. found a new method to measure internal wave energy using only the experimentally determined velocity field (Lee et al., Phys. Fluids, 26, 2014). However, this method has never been used to study the reflection of internal waves from sloping boundaries. Our previous study (Rodenborn et al. Phys., Fluids, 23, 2011) used integrated kinetic energy density as a proxy measure of the radiated wave power. Dettner et al. subsequently showed that kinetic energy density is not a good measure of the radiated wave power (Phys., Fluids, 25, 2013). They also showed that radiated wave power is weak when strong boundary flows are excited by tidal motion over model topography. We use the method of Lee et al. to analyze our experimental particle image velocimetry measurements and compare them with simulations where the energy flux is determined using the pressure and velocity fields. We find good agreement between our experimental and numerical simulation data for reflecting internal waves. We also find that there is a high rate of energy dissipation during the reflection process when the boundary flows are strongest, which occurs at the critical angle.