  Using a specially designed experimental set up, we have studied the so-called
continuous to intermittent flow transition in sand piles confined in a
Hele-Shaw cell where the deposition height of the sand can be controlled.
Through systematic measurements varying the height and the input flow, we have
established, for the first time, how the size of the pile at which the
transition takes place depends on the two parameters studied. The results
obtained allows to explain, at least semi-quantitatively, the observations
commonly reported in the literature, carried out in experiments where the
deposition height is not controlled.
