title: Pressure-driven suspension flow near jamming.
abstract: We report here magnetic resonance imaging measurements performed on suspensions with a bulk solid volume fraction (ϕ_{0}) up to 0.55 flowing in a pipe. We visualize and quantify spatial distributions of ϕ and velocity across the pipe at different axial positions. For dense suspensions (ϕ_{0}>0.5), we found a different behavior compared to the known cases of lower ϕ_{0}. Our experimental results demonstrate compaction within the jammed region (characterized by a zero macroscopic shear rate) from the jamming limit ϕ_{m}≈0.58 at its outer boundary to the random close packing limit ϕ_{rcp}≈0.64 at the center. Additionally, we show that ϕ and velocity profiles can be fairly well captured by a frictional rheology accounting for both further compaction of jammed regions as well as normal stress differences.
authors.affiliation: Schlumberger-Doll Research, One Hampshire Street, Cambridge, Massachusetts 02139, USA.
authors.forename: Sangwon
authors.initials: S
authors.lastname: Oh
authors.affiliation: Schlumberger-Doll Research, One Hampshire Street, Cambridge, Massachusetts 02139, USA.
authors.forename: Yi-qiao
authors.initials: YQ
authors.lastname: Song
authors.affiliation: Department of Civil and Resource Engineering, Dalhousie University, Halifax, Canada.
authors.forename: Dmitry I
authors.initials: DI
authors.lastname: Garagash
authors.affiliation: Schlumberger, 1 Cours du Triangle, Paris la Défense 92936, France.
authors.forename: Brice
authors.initials: B
authors.lastname: Lecampion
authors.affiliation: Schlumberger, 1 Cours du Triangle, Paris la Défense 92936, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Desroches