@article{fdi:010046765,
  title = {{I}nviscid behaviour of fines-rich pyroclastic flows inferred from experiments on gas-particle mixtures},
  author = {{R}oche, {O}livier and {G}ilbertson, {M}.{A}. and {P}hillips, {J}.{C}. and {S}parks, {R}.{S}.{J}.},
  editor = {},
  language = {{ENG}},
  abstract = {{E}xperiments were carried out on granular flows generated by instantaneous release of gas-fluidised, bidisperse mixtures and propagating into a horizontal channel. {T}he mixture consists of fine (<100 mu m) and coarse (>100 mu m) particles of same density, with corresponding grain size ratios of similar to 2 to 9. {I}nitial fluidisation of the mixture destroys the interparticle frictional contacts, and the flow behaviour then depends on the initial bed packing and on the timescale required to re-establish strong ftictional contacts. {A}t a fines mass fraction (alpha) below that of optimal packing (similar to 40%), the initial mixtures consist of a continuous network of coarse particles with fines in interstitial voids. {S}trong frictional contacts between the coarse particles are probably rapidly re-established and the flows steadily decelerate. {S}ome internal friction reduction appears to occur as a and the grain size ratio increases, possibly due to particle rolling and the lower roughness of internal shear surfaces. {S}egregation only occurs at large grain size ratio due to dynamical sieving with fines concentrated at the flow base. {I}n contrast, at alpha above that for optimal packing, the initial mixtures consist of coarse particles embedded in a matrix of fines. {F}low velocities and run-outs are similar to that of the monodisperse fine end-member, thus showing that the coarse particles are transported passively within the matrix whatever their amount and grain size are. {T}hese flows propagate at constant height and velocity as inviscid fluid gravity currents, thus suggesting negligible interparticle friction. {W}e have determined a {F}roude number of 2.61 +/- 0.08 consistent with the dam-break model for fluid flows, and with no significant variation as a function of alpha, the grain size ratio, and the initial bed expansion. {V}ery little segregation occurs, which suggests low intensity particle interactions during flow propagation and that active fluidisation is not taking place. {S}trong frictional contacts are only re-established in the final stages of emplacement and stop the flow motion. {W}e infer that fines-rich (i.e. matrix-supported) pyroelastic flows propagate as inviscid fluid gravity currents for most of their emplacement, and this is consistent with some field data. ({C}) 2005 {E}lsevier {B}.{V}. {A}ll rights reserved.},
  keywords = {volcanology ; pyroclastic flows ; analogue experiments ; fluidisation ; granular flows ; fluid gravity currents},
  booktitle = {},
  journal = {{E}arth and {P}lanetary {S}cience {L}etters},
  volume = {240},
  numero = {2},
  pages = {401--414},
  ISSN = {0012-821{X}},
  year = {2005},
  DOI = {10.1016/j.epsl.2005.09.053},
  URL = {https://www.documentation.ird.fr/hor/fdi:010046765},
}