Coarsening dynamics of granular heaplets in tapped granular layers

A semi-continuum model is introduced to study the dynamics of the formation of granular heaplets in tapped granular layers. By taking into account the energy dissipation of collisions and screening effects due to avalanches, this model is able to reproduce qualitatively the pattern of these heaplets. Our simulations show that the granular heaplets are characterized by an effective surface tension which depends on the magnitude of the tapping intensity. Also, we observe that there is a coarsening effect in that the average size of the heaplets, V, grows as the number of taps k increases. The growth law at intermediate times can be fitted by a scaling function V similar to k(z) but the range of validity of the power law is limited by size effects. The growth exponent z appears to diverge as the tapping intensity is increased.