Two-scale wave patterns on a periodically excited miscible liquid–liquid interface

Abstract

We have discovered a peculiar behaviour of the interface between two miscible liquids placed in a finite-size container under horizontal vibration. We provide evidence that periodic wave patterns created by the Kelvin-Helmholtz instability and Faraday waves simultaneously exist in the same system of miscible liquids. We show experimentally in reduced and normal gravity that large-scale frozen waves yield Faraday waves with a smaller wavelength on a diffusive interface. The emergence of the different scale patterns observed in the experiments is confirmed numerically and explained theoretically.

Characterization of fluid mixing in a closed container under horizontal vibrations

“…Finally, the concentration contours and interfacial patterns at t = 1.0 s when f = 20 Hz and A = 5.0, 6.0, and 6.5 mm from the present work are visually compared with those in Figures a–c in Shevtsova et al, respectively. They are strikingly similar.…”

“…Eventually, the small‐scale waves disappear as a thick mixing layer is formed over the columns. This phenomenon has been experimentally evidenced by Shevtsova et al and theoretically predicted by Kumar . The Rayleigh‐Taylor instability can further intensify interfacial deformation and, thus, speed up diffusion and promote mixing.…”

“…Furthermore, three different mixing regimes versus vibration amplitude and frequency are shown in Figure . The black curve shows the thresholds of secondary instability obtained by the theory of Rayleigh‐Taylor instability . The theoretical predictions are in excellent agreement with our numerical simulations.…”

“…The concentration pattern is essentially two‐dimensional except in small near‐wall regions in the direction perpendicular to the x‐y plane, which has been validated in the reduced and normal gravity environment by Shevtsova et al and Siddavaram and Homsy . The two‐dimensional numerical model has been also used to study the mixing between two miscible liquids subject to vertical vibrations by Amiroudine et al Since our main concern is the physical understanding of the phenomenon of mixing, we focus our attention on two‐dimensional effects to reduce the complexity of the problem.…”

“…The CFD model is further validated through comparing the simulation results with literature‐reported simulation results or experimental results. Shevtsova et al and Gaponenko et al investigated experimentally and numerically the flows of the two miscible liquids in the same closed vibrating container as our study. There is a perfect agreement in flow dynamics between simulations and experiments in their study, so their simulation results are used to validate our simulation model and setup.…”