... | ... | @@ -2,7 +2,14 @@ It is important to note that within the granular flows field there are many diff |
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### Friction, Cohesion and so on...
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One of the greatest advantage of the MigFlow Software is its compatibility with the [LMGC90](https://git-xen.lmgc.univ-montp2.fr/lmgc90/lmgc90_user/wikis/home) Software (for installation we recommend to follow the instructions on their website). A contact solver, named _scontact_ is provided with MigFlow to compute the velocities and trajectories of the grains, forbidding interpenetration, in a lagrangian way. It uses a time-stepping method that corrects iteratively the free velocities of the grains, obtained by applying external forces, to compute a set of velocities giving after displacement of the grains a stationary state without intersection. This solver is much faster than LMGC90 and can even taken coulomb friction into account in 2D cases, but it can be disconnected from the fluid part and replaced by LMGC90 to take advantage of the huge variety of contact laws implemented in it. Some test cases are given to present how to call LMGC90 from the Users Interface:
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The MigFlow software can take into account friction between the grains in various ways.
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Its own frictional contacts solver, _scontact_, can solve friction in both 2D and 3D for spherical grains, considering that they can rotate or not. This local solver takes advantage of the sphericity of the particles to be very fast and efficient. The forces exerted by the grains on the domain boundaries can be computed, as well as the stress tensor inside the grains. Finally, _scontact_ allows to fix some grains so that they act like a boundary, enabling the simulation of a granular flow through a fixed porous media for example.
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Another possibility is to use [LMGC90](https://git-xen.lmgc.univ-montp2.fr/lmgc90/lmgc90_user/wikis/home) Software (for installation we recommend to follow the instructions on their website), which is compatible with the fluid solver of MigFlow. This way, more complex contact laws and particle shapes can be taken into account.
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Both solvers make use of the Nonsmooth Contact dynamics, which is a time-stepping method that corrects iteratively the free velocities of the grains, obtained by applying external forces, to compute a set of velocities giving after displacement of the grains a stationary state without intersection.
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Some test cases are given to present how to call LMGC90 from the Users Interface:
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- [mill.py](https://git.immc.ucl.ac.be/fluidparticles/migflow/blob/master/testcases/couette-2d/mill.py) presents the mixing of grains with different radii in a rotating drum using LMGC90 or _scontact_ to take into account the impact of the friction on the mixing efficiency.
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- [avalanchnofluidfriction.py](https://git.immc.ucl.ac.be/fluidparticles/migflow/blob/master/testcases/avalanch/avalanchnofluid/avalanchnofluidfriction.py) presents a bidimensional grain avalanche without fluid, and shows how to use the LMGC90 software or the _scontact_ solver at choice.
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