Project title: A Multiscale Approach for the Development of New Constitutive Laws for Granular Flows

Supervisors: Berend van Wachem, Daniele Dini, Michele Marigo and Selassie Dorvlo

Project description:

Granular flow is encountered both in nature and in many industrial applications, such as the fabrication of medicines, and the mixing and fabricating of powders, to name just a few. Granular flow is everywhere. A good model describing granular flow is thus of enormous importance, as it enables us to help design and optimise industrial processes. However, currently, there is no appropriate general model for dry granular flow which builds on first principle material properties.

In this project, three different length and time-scales of granular flow will be researched. The smallest scale focuses on the actual deformation of interacting grains and is simulated using the actual properties of the grains, using the finite element method. The micro-scale behaviour of various types of impacts will be determined for various grain properties. Different frictional interactions and interface laws, such as cohesion, surface roughness and non-sphericity will be considered to shed light on individual material responses to collision.

The understanding of the micro-scale behaviour of a single impact event can then be used to construct a grain interaction model based on first principles. This model will be used on a meso-scale by modelling a large number of individual grains (~106) as spheres in an existing computational discrete element framework. In this framework, effects such as cohesion, homogeneity, material properties and surface roughness are taken into account.

Finally, simulations of granular flow on piles, chutes and shear cells will be pursued and validated against both available experimental data and new experiments carried out by industrial collaborators Johnson Matthey. These simulations can provide an abundance of data, which will be used to derive continuum constitutive laws for dense granular flows. These constitutive laws will be used to model complex and realistic granular flows on a macro-scale in geophysical and industrial applications.