Experimental study of the mutual interactions between waves and tailored turbulence.

Autor: Smeltzer BK; Department of Energy and Process Engineering, Norwegian University of Science and Technology, N-7491, Trondheim, Norway.; SINTEF Ocean, Marinteknisk senter, N-7052 Trondheim, Norway., Rømcke O; Department of Energy and Process Engineering, Norwegian University of Science and Technology, N-7491, Trondheim, Norway., Hearst RJ; Department of Energy and Process Engineering, Norwegian University of Science and Technology, N-7491, Trondheim, Norway., Ellingsen SÅ; Department of Energy and Process Engineering, Norwegian University of Science and Technology, N-7491, Trondheim, Norway.
Jazyk: angličtina
Zdroj: Journal of fluid mechanics [J Fluid Mech] 2023 May 10; Vol. 962, pp. R1.
DOI: 10.1017/jfm.2023.280
Abstrakt: When surface waves interact with ambient turbulence, the two affect each other mutually. Turbulent eddies get redirected, intensified and periodically stretched and compressed, while the waves suffer directional scattering. We study these mutual interactions experimentally in the water channel laboratory at the Norwegian University of Science and Technology (NTNU) Trondheim. Long groups of waves were propagated upstream on currents with identical mean flow but different turbulence properties, created by an active grid at the current inlet. The subsurface flow in the spanwise-vertical plane was measured with stereo particle-image velocimetry. Comparing the subsurface velocity fields before and after the passage of a wave group, a strong enhancement of streamwise vorticity is observed which increases rapidly towards the surface for k 0 z ≳ -0.3 ( z : vertical distance from still surface; k 0 : carrier wavenumber) in qualitative agreement with theory. Next, we measure the broadening of the directional wave spectrum at increasing propagation distance. The rate of directional diffusion is greatest for the turbulent case with the highest energy at the longest length scales whereas the highest total turbulent kinetic energy overall did not produce the most scattering. The variance of directional spectra is found to increase linearly as a function of propagation time.
Competing Interests: Declaration of interests. The authors report no conflict of interest.
Databáze: MEDLINE
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