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Ultrasound Propagation in Cohesive Granular
Materials
Thomas Brunet, Xiaoping Jia, Pascale Massaad,
Pierre Mills
propagation of elastic wave in dense granular
media under stress
P
P
Polydisperse glass beadsd 600-800 µm
L
l gtgt dCoherent Ballistic Wave (E)
l dMultiple Scattering Wave (S), i.e.
acoustic speckles
Dry bead packing
Wet bead packing by oil F 0,015
(Jia et al, PRL 1999 PG 2001)
(Jia, PRL 2004)
Diffusive transport of multiple scattering waves
Measurements of compressional (L) and shear (T)
wave velocities providing elastic modulii (K, G)
Effective Medium Theory (hertzian scaling law)

where
Short correlation length of force chains
probing cohesive granular material with elastic
waves
Energy dissipation in a wet granular medium
Capillary effects on the structure and elastic
properties (all liquids)
Decreasing the geometric coordination number due
to the adhesion by liquid bridges
Lubrication effects on the elastic
properties(only trioléïne)
Mechanism of contact recruitment due to the
presence of the adsorded liquid films
wetting liquid increase dramatically dissipation
in the medium, especially when the liquid is
lubricant
Ultrasonic absorption measurements with
controlled grain surfaces and wetting liquids
Understanding the dissipation mechanism
Current Study
where the active coordination number Zwet(P)
is significantly increased due to lubrication.