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Flow Behavior of Clay‐Silt to Sand‐Silt Water‐Rich Suspensions at Low to High Shear Rates: Implications for Slurries, Transitional Flows, and Submarine Debris‐Flows
Author(s) -
DEL GAUDIO Pierdomenico,
VENTURA Guido
Publication year - 2018
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/1755-6724.13735
Subject(s) - silt , slurry , geotechnical engineering , geology , submarine , debris flow , shear (geology) , flow (mathematics) , debris , environmental science , geomorphology , environmental engineering , petrology , oceanography , geometry , mathematics
Water‐rich clay to sand suspensions show a shear rate dependent flow behavior and knowledge of the appropriate rheological model is relevant for sedimentological, industrial and hydraulic studies. We present experimental rheological measurements of water‐rich (40 to 60 wt%) clay to silt (population A) and silt to sand (population B) suspensions mixed in different proportions. The data evidence a shear rate dependent shear thinning‐shear thickening transition. At lower shear rates, the suspensions organize in chains of particles, whereas at higher shear rates, these chains disrupt so increasing the viscosity. The viscosity, consistency and yield stress decrease as the A+B fraction decreases as the content of B particles increases. This behavior reflects the competing effects of the lubrication and frictional processes as a function of particle size and water content. Transitional flows form by the incorporation of small amounts of the finer fraction while ‘oceanic floods’ form at the estuary of rivers and the submarine debris‐flows increase their velocity by incorporating water. The critical Reynolds number of the studied suspensions is ∼2000±100 suggesting that the grainsize plays a major role in the laminar to turbulent transition. Our results have implications for the modeling of sediment flows and the hazard related to floods.