Scale separation between grain detachment and grain transport in granular media subjected to an internal flow.

Séparation d'échelle du détachement et du transport de grains dans un milieu granulaire soumis à un écoulement interne

A. Wautier (1) , Stéphane Bonelli (1) , François Nicot (2)

1 RECOVER - Risques, Ecosystèmes, Vulnérabilité, Environnement, Résilience
2 UR ETGR (ETNA) - Erosion torrentielle neige et avalanches

Based on a discrete element method (DEM), this paper investigates the basic mechanisms and the associated scales related to grain detachment and grain transport processes, at stake in widely graded poly-disperse assemblies of spheres subjected to internal fluid flows. From the identification of force chains, particles sensitive to grain detachment are identified. Based on the computation of autocorrelation lengths, a typical length scale associated with this phenomenon is then defined. From the characterization of the void space as a pore network, particles eligible for, grain transport are identified among the detachable particles. Based on the definition of a mean travel distance, the typical length scale associated with grain transport is finally characterized. The comparison between the two length scales highlights a scale separation between grain detachment and grain transport.

Mots clés: micromechanics; discret element method; granular flow; Mesoscales; Force chains; Autocorrelation; Pore Network

Mots clés: MICROMECANIQUE; METHODE DES ELEMENTS DISCRETS; MILIEU POREUX; ECOULEMENT EN MILIEU POREUX; ECOULEMENT GRANULAIRE

Domaines: Sciences de l'environnement

A. Wautier, Stéphane Bonelli, François Nicot. Scale separation between grain detachment and grain transport in granular media subjected to an internal flow.. Granular Matter, 2017, 19 (2), 15 p. ⟨10.1007/s10035-017-0706-9⟩. ⟨hal-01720370⟩