We propose an experimentally derived constitutive equation for dense granular-fluid mixture (e. g. debris-flow). It is based on frictional (quasi-static) and collisional (dynamic) stress component. The model has been compared with experiments carried out in an annular rheometer (Angeloni, Lamberti, Schippa 19971) using glass spheres and natural sand shearing in air and in newtonian viscous fluids (i. e. water and water-glycerol solution) having different viscosity. The measures of the velocity distribution inside the channel leads to the a characterization of the actual shearing layer and to the evaluation of the related parameters (e. g. concentration, shear rate, etc). Dynamic stress component is consistent with that originally proposed by Bagnold (1954) in the asymptotic grain-inertia regime, but in the macro-viscous regime the value of the constant scatter from the original one, because of the presence of the quasi static stress component. The weighted function related to the quasi-static and dynamic stress seems to be slightly dependent on the grain characteristics (i. e. mainly the shape) in the range of the experiments. The constitutive model herein proposed compare satisfactorily with our experiments.

Constitutive relation for dense granular flow

SCHIPPA, Leonardo
Primo
;
LAMBERTI, Alberto
Ultimo
1999

Abstract

We propose an experimentally derived constitutive equation for dense granular-fluid mixture (e. g. debris-flow). It is based on frictional (quasi-static) and collisional (dynamic) stress component. The model has been compared with experiments carried out in an annular rheometer (Angeloni, Lamberti, Schippa 19971) using glass spheres and natural sand shearing in air and in newtonian viscous fluids (i. e. water and water-glycerol solution) having different viscosity. The measures of the velocity distribution inside the channel leads to the a characterization of the actual shearing layer and to the evaluation of the related parameters (e. g. concentration, shear rate, etc). Dynamic stress component is consistent with that originally proposed by Bagnold (1954) in the asymptotic grain-inertia regime, but in the macro-viscous regime the value of the constant scatter from the original one, because of the presence of the quasi static stress component. The weighted function related to the quasi-static and dynamic stress seems to be slightly dependent on the grain characteristics (i. e. mainly the shape) in the range of the experiments. The constitutive model herein proposed compare satisfactorily with our experiments.
1999
dense granular flow, debris-flow, rheology, experiments
File in questo prodotto:
File Dimensione Formato  
Constitutive_Relation_for_Dense_Granular_Flow.pdf

accesso aperto

Tipologia: Full text (versione editoriale)
Licenza: PUBBLICO - Pubblico con Copyright
Dimensione 161.91 kB
Formato Adobe PDF
161.91 kB Adobe PDF Visualizza/Apri

I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/472525
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact