Our research group studies systems in which physical and mechanical processes with distinct characteristic scales (large versus small, slow versus fast, localized versus collective) are equally important – and interacting. To overcome this multi-scale challenge, the group develops and applies high-performance computing, advanced algorithms, statistical, continuum and micro-macro theories, as well as experiments. Most applications involve combining numerical methods and theories from fluid and solid mechanics. Examples include particles suspended in (non-) Newtonian fluids, molecular flow through nano-porous media, micro-structured modern materials, and granular systems displaying both solid-like and fluid-like behaviour depending on the prevailing conditions. Industrially relevant multi-scale systems are too big to be simulated with a single monolithic method, and hence it is essential that multi-scale methods are being developed by a research group that brings together a combination of disciplines and expertises.

The mission of the Multi Scale Mechanics (MSM) group is to establish itself as the ’source of knowledge’ in the fields of fluids and solids, particles and their contacts, granular materials and powders, self-assembling and self-healing materials, micro- and nano-fluidics and biological systems.

granular packing

Mechanics and structure of granular assemblies

Granular materials present a different mechanical behaviour than classical solids and fluids, as their behaviour depends on the complex contact forces and network of the constituent particles. In our group, we study different element tests of granular packings with the general goal of relating micro-structure and contact laws to the constituive relations of a continuum, macro description.

For a general introduction to the subject, click here to see Stefan Luding's talk at the Kavli Institute for Theoretical Physics (University of California), on October, 2014.

Vibrated granular systems

Agitated granular systems present behaviours which are excelent examples of non-equilibrium steady states. Their study can lead to a better general understanding of non-linear dynamics of many particle systems. In our group we focus on the vertically agitated narrow bed geometry, a setup that presents many interesting states and complex transitions between them. Our approach consists in the elaboration of continuum theories that capture the observed behaviours, and the comparisson of particle simulations with granular hydrodynamics equations.

Freely cooling systems

Dissipation, together with excluded volume, are the two most important characteristics of granular media. Freely cooling granular gases present coexistence of extremely dilute regions with very high density solid clusters. The basic idea of clustering is that in an initially homogeneous state, fluctuations in density, velocity, and temperature cause a position dependent energy loss. In our group we study the dynamics of such states as a function of the interaction law between particles, as also for polydisperse cases.

Computational modeling of non-Newtonian flows in nano-channels

In the present project the goal is to study the non-Newtonian transport properties of such fluids, investigate the effect of wall-fluid interaction, surface roughness and wall-morphology on the flow behavior.

Modeling of long-range interaction forces and clustering phase diagram

The objective of this project is to develop a three dimensional Molecular Dynamics (MD) environment and hydrodynamic theory for modeling long-range interaction forces based on hierarchical algorithms.