APS -70th Annual Meeting of the APS Division of Fluid Dynamics- Event - Measuring Energy Dissipation in Reflecting Internal Waves using PIV Data

摘要

We previously conducted experiments and simulations that tested weakly nonlineartheories (Rodenborn et. al., Phys. Fluids, 2011) of internal wave reflection from asloping boundary. In the previous study, we used integrated kinetic energy as a measureof internal wave beam energy. However, we use an algorithm by Lee et al. (Phys. Fluids,26, 2014) to determine the energy flux of internal waves in our experiments using velocityfield (PIV) measurements. We find good agreement between our laboratory data and ournumerical simulations, where the energy flux is determined from the velocity and pressurefields. We also calculate the rate at which energy is dissipated in the reflection process byfinding the energy flux into and out of a surface above the reflection region Eout=Ein. Wefind high rates of energy dissipation O(90%) near the critical angle in both experimentsand simulations. High dissipation at the critical angle occurs in our simulations even forweakly nonlinear wave beams and when the viscosity reduced by an order of magnitude,which implies that dissipation may be relevant to internal wave reflection in the ocean.