How To Simulate superquadric particles in liggghts and make them visible in paraview 5.8

Liggghts must be compiled with USE_SUPERQUADRICS = "ON" in makefile.user in the src/MAKE/ folder

Liggghts simulation setup:

use your normal simulation file. Change following lines: ( your settings may be different, change accordingly)

atom_style granular

-->

atom_style superquadric

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pair_style gran model hertz tangential history cohesion sjkr rolling_friction cdt

-->

pair_style gran model hertz tangential history cohesion sjkr rolling_friction cdt surface superquadric

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fix granwalls all wall/gran model hertz tangential history cohesion sjkr rolling_friction cdt mesh n_meshes 1 meshes cad

-->

fix granwalls all wall/gran model hertz tangential history cohesion sjkr rolling_friction cdt surface superquadric mesh n_meshes 1 meshes cad

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fix pts1 all particletemplate/sphere 15485863 atom_type 1 density constant ${DENSITY} radius constant ${RADIUS}

-->

fix pts1 all particletemplate/superquadric 15485863 atom_type 1 density constant 2500 shape constant ${RADIUS1} ${RADIUS2} ${RADIUS3} blockiness constant ${BLOCK1} ${BLOCK2}

Play arround in parraview (next chapter) to find your desired shape

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fix integr all nve/sphere

-->

fix integr all nve/superquadric

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for dumping use:

dump dmp2 all custom/vtk 2000 post/dump*.superq.vtk type mass x y z id vx vy vz fx fy fz omegax omegay omegaz radius shapex shapey shapez quat1 quat2 quat3 quat4 blockiness1 blockiness2 tqx tqy tqz angmomx angmomy angmomz

Paraview Setup (Version 5.8)

1. Load dump*.superq.vtk
2. Add Sources --> Superquadric
   • Center 0,0,0
   • Theta Roundness is 2/${BLOCK1}
   • Phi Roundness is 2/${BLOCK2}
   • untoggle Toroidal
3. Add a transform filter to Superquardic
   • rotate in x axis by 90 (°)
   • scale your particle to your particle size
     • x scale is ${RADIUS1}*2
     • y scale is ${RADIUS3}*2
     • z scale is ${RADIUS2}*2
   • if you want to see the overall dimensions of your particle go to the "information" tab. (Bounds, delta for each dimension is the size in m (usually ))
4. ctrl+ click on dump*.superq.vtk and Superquadric (first dump, than superquadric)
   • apply programmamble filter
   • Output : vtkUnstructuredGrid
   • Code: copy from transform_filter_superquadric_with_colors.py
5. Apply and enjoy

Credits

User: martin.kozakovic and richti83

on website www.cfdem.com

Sources:

https://www.cfdem.com/forums/tutorial-4-superquadric-angle-repose-representation-python-filter