An agglomerate made of solid particles held together by
a viscous liquid phase when
sheared in an otherwise dry granular material is observed to deform by
stretching.
This observation, based on experimental results, is confirmed in the present
paper by
means of a computer simulation model. Simulations as well as experimental
results
indicate that the degree of deformation by stretching, a critical factor
influencing
the stability of such agglomerates, is governed by a dimensionless parameter
of the
system, called the deformation Stokes number, Stdef.
Two regimes, involving high and
low characteristic degrees of deformation, can be identified based upon
the value of
this number. Simulation results indicate that for the range of conditions
simulated,
the value separating the two regimes, the critical deformation Stokes
number, St*def,
is relatively insensitive to the agglomerate size and other parameters
of the system.
This critical number defines the conditions below which forces inducing
agglomerate
breakage are low and above which they are high and result in agglomerate
break-up. Calculation and/or measurement of this parameter is
essential for prediction of
equilibrium sizes of agglomerates in industrial granulation operations.