Brownian forces in sheared granular matter.
We present results from a series of experiments on a granular medium sheared in a Couette geometry and show that their statistical properties can be computed in a quantitative way from the assumption that the resultant from the set of forces acting in the system performs a Brownian motion. The same assumption has been utilized, with success, to describe other phenomena, such as the Barkhausen effect in ferromagnets, and so the scheme suggests itself as a more general description of a wider class of driven instabilities.
Baldassarri
A
A
Dipartimento di Fisica, Università La Sapienza, Piazzale le Aldo Moro 2, 00185 Roma, Italy.
Dalton
F
F
Petri
A
A
Zapperi
S
S
Pontuale
G
G
Pietronero
L
L