2025/12/17 by Andrés Castillo-Castellanos, Castillo-Castellanos, Andrés, Benoît-Joseph Gréa +5 · 1 citation
Computer Science · Engineering · Materials Science · #Fluid Dynamics and Thin Films #Nonlinear Dynamics and Pattern Formation #Solidification and crystal growth phenomena #physics.flu-dyn
paper · pdf · doi:10.48550/arxiv.2512.15536
openalex publication_date 2025/12/17 · openalex created_date 2025/12/19 · openalex updated_date 2026/07/28
We investigate how surface waves enhance mixing across the interface between two miscible fluids with a small density contrast. Imposing a vertical, time-periodic acceleration, we excite Faraday waves both experimentally and numerically. In systems with a shallow density gradient, these standing waves advect the interface and can trigger secondary instabilities. When driven beyond the linear regime, large Faraday crests collapse to form cavities, injecting bubbles and lighter fluid deep into the heavier layer. Together, these mechanisms gradually homogenize the upper layer, diminish the interfacial density jump, and drive the interface downward until it decouples from surface forcing. We report a non-monotonic mixing rate -- first increasing as the interfacial energy barrier lowers, then decreasing as less energy is injected into the weakened surface -- revealing a balance between barrier reduction and energy input. Based on these observations, we introduce a one-dimensional model incorporating a turbulent diffusivity coefficient that depends on depth and the internal Richardson number, which captures the qualitative evolution of the system.