granular flow
Gravity drives most granular shear flows including geologic situations (from landslides to sand piles on a beach) and industrial applications (processing of powders and grains). Our understanding of gravity-driven granular flows is based almost exclusively on experiments under Earth's gravity, g0.
The research activities focus on effect of gravity on the fundamental surface and subsurface granular flows. This is of particular importance in the investigation of the geology of planets and asteroids.
experimental setup
A small rotating tumbler, partially filled with glass beads is mounted in a rack that can be flown with the institute's centrifuge which provides the means of varying the 'gravitational' acceleration. The acceleration is measured with high precision accelerometers while the flow is observed with digital cameras.
results
The determination of the dynamic angle of repose as a function of tumbler rotational speed, tumbler radius, and gravitational acceleration enables us to validate that the Froude number describes the nature of the granular flow.
Currently the influence of gravitational level on the subsurface flow is investigated by examining core precession and erosion.
publications, talks and posters
2006
T. Arndt, A. Brucks, J. M. Ottino, and R. M. Lueptow: Creeping Motion Under Variable Gravity Levels, Phys. Rev. E 74, 031307 (2006).
A. Brucks, T. Arndt, J. M. Ottino, and R. M. Lueptow: Behaviour of granular materials under variable g, accepted by Phys. Rev. E (2006).
Brucks, A., Arndt, T., Lueptow, R. M.: Behaviour of granular flow under variable gravitational level, DPG annual spring meeting, Dresden, March 26-31, (2006).
Lueptow, R. M., Arndt, T., Brucks, A., Ottino, J. M.: Fundamental characteristics of granular flow under variable g-levels, 10th ASCE Aerospace international conference on Engineering, Construction and Operations in Challenging Environments, League City/Houston, March 5-8, (2006).
2005
Brucks, A., Ottino, J. M., Lueptow, R. M.: Granular Flow ina tumbler under variable g-levels, APS 58th annual meeting of the devision of of fluid dynamics, Nov. 20-22, Chicago, (2005).
Arndt, T.: Creeping motion of granular flow in a rotating quasi 2D tumbler under variable gravity conditions, Diploma thesis, University of Bremen, Zarm, (2005).
Brucks, A., Arndt, T., Kassai, H., Oelze, H., Odenbach, S., Lueptow, R. M.: Rotating granular flow: varying the Froude number by varying g, DPG annual spring meeting, Berlin, March 4-9, (2005).
2004
Arndt, T.: Untersuchung von granularen Medien in einer Quasi-2D-Zelle, Studienarbeit, University of Bremen, Zarm, (2004).
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