Sediment motion induced by Faraday waves in a Hele-Shaw cell.

The interaction between the oscillatory boundary-layer flow induced by Faraday waves and a sedimentary granular layer was studied in a Hele-Shaw cell vertically vibrated. The experimental parameters were the vibration frequency f and acceleration a and the particle diameter d_{p}. At a critical value for the depth of the supernatant fluid layer Δh_{c}, a transition between a flat motionless granular layer and a second regime in which the granular layer undulates and oscillates periodically was observed.

Faraday waves over a permeable rough substrate.

We report on an experimental study of the Faraday instability in a vibrated fluid layer situated over a permeable and rough substrate, consisting either of a flat solid plate or of woven meshes having different openings and wire diameters, open or closed (by a sealing paint). We measure the critical acceleration and the wavelength (on the images from top) at the onset of the instability for vibration frequencies between 28 and 42 Hz. We observe that, in comparison with the flat plate, a mesh leads to an increase of the critical acceleration, whereas the wavelength is not significantly altered in none of the explored cases.