Viscous reflection of internal waves from a slope

Kataoka, Takeshi; Akylas, T. R.

doi:10.1103/physrevfluids.5.014803

Cited by 8 publications

(5 citation statements)

References 23 publications

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“…The largest contribution is associated to the frequency ω 0 /N = 0.26, which comes from the incident and the reflected wave. As expected and already studied (Tabaei et al 2005;Rodenborn et al 2011;Kataoka and Akylas 2020), one can observe higher order frequencies (2ω 0 , 3ω 0 , etc.) with lower magnitude and a non vanishing contribution to the signal at ω/N = 0.…”

Section: Temporal Filteringsupporting

confidence: 86%

Variational Mode Decomposition for estimating critical reflected internal wave in stratified fluid

Horne,

Schmitt,

Pustelnik

et al. 2020

Preprint

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The shear resulting from internal wave reflections can play a crucial role in the transport and resuspension of sediments in oceanic conditions. In particular, when these waves undergo a critical reflection phenomenon, the reflected wave can produce a very large shear. Separating the reflected wave from the incident wave is a technical challenge since the two waves share the same temporal frequency. In our study, we present a series of experimental measurements of internal waves in critical reflection configuration and we analyze them using the 2D-VMD-prox decomposition method. This decomposition method was adapted to specifically decompose waves in an internal wave critical reflection, showing an improvement in its performance with respect to preexisting internal wave decomposition methods. Being able to confidently isolate the reflected wave allowed us to compare our results to a viscous and nonlinear model for critical reflection, that correctly describes the dependence of the shear rate produced in the boundary as a function of the experimental parameters.

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Section: Temporal Filteringsupporting

confidence: 86%

Variational Mode Decomposition for estimating critical reflected internal wave in stratified fluid

Horne,

Schmitt,

Pustelnik

et al. 2020

Preprint

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“…Chalamalla et al (2013) reported that the turbulent kinetic energy can be higher for somewhat off-critical reflection compared to exactly critical reflection under certain conditions. A weakly nonlinear model (Kataoka & Akylas 2020) also shows that in some conditions, the viscous effect can be important during the wave reflection from a slope, which leads to the deviation of the optimal off-criticality from zero.…”

Section: Profiles Of Dissipation Rate and Kinetic Energymentioning

confidence: 99%

A laboratory study of internal gravity waves incident upon slopes with varying surface roughness

Cheng

Xia

2022

J. Fluid Mech.

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We report a laboratory study on the scattering, energy dissipation and mean flow induced by internal gravity waves incident upon slopes with varying surface roughness. The experiment was performed in a rectangular box filled with thermally stratified water. The roughness of the slope surface, $\lambda$ , defined as the height of a roughness element over its base width, and the off-criticality $\gamma =(\alpha -\beta )/\beta$ , with $\alpha$ and $\beta$ being the angles of the incident wave and the slope, are used as two control parameters. The distribution of energy dissipation in the direction normal to the slope is found to be more uniform in the rough surface cases. Counter-intuitively, both the maximum value in the dissipation profile and the total energy dissipation near the slope are reduced by surface roughness under most circumstances. The measured peak width (the full width at half-maximum of the peaks) of the dissipation profile is found to be broadened significantly in the rough surface cases. We also observed that there exists a non-zero optimal off-criticality ( $\gamma =0.17$ for the present measurement resolution) for the normalized average dissipation and total dissipation, which may be due to the strongest wave energy near the slope at this $\gamma$ . Unlike surface roughness, the off-criticality has a small effect on the distribution of energy dissipation. Moreover, surface roughness is also found to change the structure of the scattering-induced mean flow and enhance its strength. The present study provides new perspectives on how the surface roughness on topographic features influences energy dissipation.

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“…Furthermore, similar to in (4.1), the forcing amplitude parameter in (4.2) is chosen such that the integral in the central vertical plane () of the numerically computed mean-flow velocity in the direction at 20 beam periods matches the value of this integral based on the experimental mean-flow data at the same time. The Navier–Stokes equations are solved numerically by adapting to the present three-dimensional geometry the procedure outlined in Kataoka & Akylas (2020) for two-dimensional reflection of an internal wave beam from a rigid slope. The results reported here were obtained using the computational domain with grid points and the time step s. The grid points were more concentrated near the wave generator in order to achieve higher resolution there.…”

Section: Comparison Of Theory With Experimentsmentioning

confidence: 99%