Session: 04-07-02: Interfacial Phenomena and Flows

Paper Number: 130436

130436 - Interaction Between Capillary Waves and Hydrodynamic Turbulence in a Two-Layer Oil-Water Flow 

We study the dynamics of capillary waves at the interface of a two-layer stratified turbulent channel flow. We use a combined pseudo spectral/phase field method to solve for the turbulent flow in the two liquid layers and to track the dynamics of the liquid/liquid interface. The two liquid layers have same thickness and same density, but different viscosity. We vary the viscosity of the upper layer (two different values) to mimic a stratified oil-water flow. This allows us to study the interplay between inertial, viscous and surface tension forces in the absence of gravity. In the present setup, waves are naturally forced by turbulence over a broad range of scales, from the larger ones, whose size is of order of the system scale, down to the smaller dissipative scales. After an initial transient, we observe the emergence of a stationary capillary wave regime, which we study by means of temporal and spatial spectra. The computed frequency and wavenumber power spectra of wave elevation are in line with previous experimental findings and can be  explained in the frame of the weak wave turbulence theory. Finally, we show that the dispersion relation -- which gives the frequency (w) as a function of the wavenumber (k) -- is in good agreement with the well established theoretical prediction, w(k) \sim k^3/2.

Presenting Author: Francesco Zonta TU Wien