2016/08/01 by Yvan Dossmann, Y. Dossmann, B. Bourget +9 · 2 citations
Earth and Planetary Sciences · Environmental Science · Physics and Astronomy · #Acoustics #Climate variability and models #Computer science #Dispersion (optics) #Gravity wave #Internal wave #Mechanics #Meteorological Phenomena and Simulations #Mixing (physics) #Noise (video) #Oceanographic and Atmospheric Processes #Optics #Particle image velocimetry #Physics #Stratified flow #Stratified flows #Turbulence #Velocimetry #Wave propagation #physics.flu-dyn
paper · pdf · doi:10.1007/s00348-016-2212-y
published as Experiments in Fluids 57, 132 (2016)
openalex publication_date 2016/08/01 · arxiv created 2018/05/11 · arxiv updated 2021/02/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a novel characterization of mixing events associated with the propagation and overturning of internal waves, studied thanks to the simultaneous use of Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF) techniques. This combination of techniques had been developed earlier to provide an access to simultaneous velocity and density fields in two-layer stratified flows with interfacial gravity waves. Here, for the first time, we show how it is possible to implement it quantitatively in the case of a continuously stratified fluid where internal waves propagate in the bulk. We explain in details how the calibration of the PLIF data is performed by an iterative procedure, and we describe the precise spatial and temporal synchronizations of the PIV and PLIF measurements. We then validate the whole procedure by characterizing the Triadic Resonance Instability (TRI) of an internal wave mode. Very interestingly, the combined technique is then applied to a precise measurement of the turbulent diffusivity Kt associated with mixing events induced by an internal wave mode. Values up to Kt=15 mm2⋅ s-1 are reached when TRI is present (well above the noise of our measurement, typically 1 mm2⋅ s-1), unambiguously confirming that TRI is a potential pathway to turbulent mixing in stratified flows. This work therefore provides a step on the path to new measurements for internal waves.