A.Garcimartín, D. Maza, J. L. Ilquimiche and I. Zuriguel, ""Convective motion in a vibrated granular layer"". Phys. Rev. E, vol. 65, p. 031303, (2002).
Velocity measurements are presented for a vertically shaken granular layer. For frequencies around 110 Hz
and accelerations larger than gravity, the layer develops a convective motion in the form of one or more rolls.
The velocity of the grains near the wall has been measured. It grows linearly with the acceleration, then the
growth rate slows down. A rescaling with the amplitude of the wall velocity and the height of the granular layer
makes all data collapse in a single curve.