ABSTRACT
Recent experimental and numerical studies have allowed the measurement of rheological laws in dense granular flows (Pouliquen & Chevoir 2002; GDR MIDI 2004; da Gruz et al. 2005). Several studies have revealed strong correlations of motion and force (Radjai & Roux 2002; Bonamy et al. 2002; Mueth 2003; Chambon et al. 2003; Ferguson et al. 2003; Pouliquen 2004). The observation of those dynamic heterogeneities have motivated the development of various non-local models (Pouliquen & Forterre 2001; Andreotti & Douady 2001; Chevoir et al. 2001; Lemaitre 2002; Ertas & Halsey 2002; Rajchenbach 2003; GDR MIDI 2004; Picard et al. 2005). Following a previous model (Mills et al. 1999; Bonamy & Mills 2003), we describe dense granular flows as transient rigid clusters immersed in a viscous fluid made of free grains interacting through collisions. Using molecular dynamics simulations described in Rognon et al. (2005), we identify candidates for those rigid structures, and measure their characteristics. Then we propose a rheological biphasic model with a non-local coupling term between the viscous fluid and the rigid clusters. At the end, we discuss the prediction of this model for jamming.
