From soft and hard particle simulations to continuum theory for granular flows

One challenge of today’s research is the realistic simulation of disordered many particle systems in static and dynamic/flow situations. Examples are particulate and granular materials like sand, powders, ceramics or composites, with applications in particle-technology and geo-technical/physical systems. The inhomogeneous microstructure of such materials makes it very difficult to model them with continuum methods, which typically assume homogeneity on the microscale and scale separation between the constituents and the macroscopic fields. As an alternative, discrete particle methods can be applied, since they intrinsically take the micro-structure into account. The ultimate challenge is to bridge the gap between both approaches by using particlesimulations to obtain appropriate constitutive relations for continuum theories, and work with those on the macro-scale. Here, soft and hard particle simulation methods are introduced as well as the micro-macro transition to obtain the continuum fields from the particle data. Two application examples discussed in detail concern the flow of particle down an incline, as relevant for geo-flows, as well as a vibrated granular system as relevant for highly agitated transport or conveying processes.