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CoRheoGrain - Complex Rheology Grain Solver
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The Complex Rheology Grain Solver is developed to deal with the flows of granular materials (for example sand). To deal with industrial problems two competing goals have to be met:
- The whole range of the complex three dimensional dynamic behaviour of granular flow has to be reproduced as realistic as possible
- The computation time must be short enough for the use in an industrial environment.
Both requirements are best fulfilled by using a special nonlinear hydrodynamic model, which has been developed at the ITWM. Our hybrid model combines the characteristics of rapid granular flow with ansatzes from soil mechanics for dense slow flows. It reproduces known results from granular dynamics as e.g. dilatancy, existence of shear bands and solid like behaviour.
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Application Examples
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Silo Flows:
A basic effect of silo flow is the distinction of core and mass flow depending on the steepness of the silo cone, the wall stress and the internal friction of the granular material. For flat silos, so called core flow occurs where the grains flow towards the centre of the silo and only in the centre a flow towards the outlet occurs. For steep silos, the grains flow downwards at every point in the silo, no inverse core in the centre is observable and mass flow occurs. Not only this can be reproduced in our simulations, but also the full velocity field including the size of the stagnant zone and the pressure distribution in the silo is predicted.
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 Animation [523,1 KB, AVI]
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Coreshooting:
Sand cores are widely used in the casting industry for casting complicated machine parts. They are produced by shooting a pressurized sand air mixture with high velocity in a core box, which has to be filled as homogeneously as possible. To obtain a homogeneously filled form, vents have to be drilled at appropriate positions in the core box to avoid blocking of the sand flow e.g. due to compressed air pockets. Simulation of the whole core shooting process will help to find the optimal positions for the vents depending on the geometry of the core box and the properties of the sand. The sand dynamic is coupled to the compressible Navier-Stokes equation for air.
Figures show the sand flow prediction in the meander geometry (VIGI project). The first plot shows the experimental results (performed by the Institute für Gießereitechnik in Duesseldorf) and the second plot shows the simulation results.
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Animation [3.8 MB, MPEG]
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Pile Formation:
We are able to simulate a sandpile with predictable slopes, which is shown in the figures beside.
- Left figure: angle of repose approximately 25 degree.
- Right figure: angle of repose approximately 15 degree.
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Animation [291.9 KB, AVI]
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"Sand Flow with Obstacles":
The simulation shows the behaviour of a simple non cohesive granular material in double step geometry.
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© Fraunhofer ITWM
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This website is optimized for Mozilla Firefox Browser. Last Update: Sat-12 Jul 2008 |
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Animation [3.8 MB, MPEG]
