Soft Matter Dynamics

Understanding the movement of granules – improving industrial processes

Granular media are made up of small particles. The ESA Soft Matter Dynamics experiment (SoMaDy) will capture and describe the dynamics of granular material. As a national provision, sample cells (CompGran) are being manufactured on behalf of the DLR Space Administration for the Soft Matter Dynamics installation. In this, the dynamics of granulates of various densities are being examined. These dynamics are of great importance for industrial operations, such as the processing of grain and plastic granules. As the granules fall to the bottom of their container very quickly on Earth, their dynamics can only be investigated under microgravity conditions. The movement of the granules is examined using a technique known as dynamic light scattering. Here, the light scattered by individual particles is analysed to obtain information on the particle size and dynamics. Of particular interest are the transitions between different states of the granules, such as from a fluid like behaviour to a solidifed state. If a granular medium is liquid at first, the granules block one another when the packing density is slightly increased, hindering further movement. In ground reference measurements, the ‘dynamic light scattering’ analytical method will initially be developed and established in general for granular media. To this end, simulations and dynamic light scattering are used on reference systems, supplemented with X-ray imaging and X-ray tomography measurements. The results obtained will then be transferred to experiments on board the ISS.

In addition to liquids, granules are the most processed goods by quantity. In situ monitoring of industrial processes where granules occur is still diffcult due to a lack of analytical procedures. These experiments should, on the one hand, unlock the behaviour of granules and facilitate theoretical descriptions of it. On the other hand, measurement procedures will be developed for in situ analyses of granular media, which is also of great interest for the monitoring of industrial processes.

German Aerospace Center (DLR)
Thomas Driebe · E-Mail: ·