Additional documentation (idaholab#367)

README.md

@@ -28,6 +28,12 @@ Idaho National Laboratory is a cutting edge research facility which is a constan
 
 [Unsupported Open Source Software](https://github.com/IdahoLabCuttingBoard)
 
+### Contrib
+
+Part of this code uses the exact calculation of the [overlap](contrib/overlap/README.md) volume of spheres
+and mesh elements routines copyright (C) 2015-2018 by Severin Strobl
+<git@severin-strobl.de> (http://dx.doi.org/10.1016/j.jcp.2016.02.003).
+
 ### License
 
 Copyright 2017 Battelle Energy Alliance, LLC

doc/content/source/auxkernels/MDGranularPorosityAux.md

@@ -0,0 +1,16 @@
+# MDGranularPorosityAux
+
+!syntax description /AuxKernels/MDGranularPorosityAux
+
+Computes porosity $\phi$ or packing fraction $1 - \phi$ and injects it into and aux variable.
+The packing fraction is obtained from an `MDRunBase` object. The `MDRunBase` object needs
+to operate in `granular` mode which is triggered by providing the `radius` property
+in the `md_particle_properties` parameter.
+
+!syntax parameters /AuxKernels/MDGranularPorosityAux
+
+!syntax inputs /AuxKernels/MDGranularPorosityAux
+
+!syntax children /AuxKernels/MDGranularPorosityAux
+
+!bibtex bibliography

doc/content/source/auxkernels/MDGranularPropertyAux.md

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+# MDGranularPropertyAux
+
+!syntax description /AuxKernels/MDGranularPropertyAux
+
+Injects properties collected for MD particles from MDRunBase object user_object into auxiliary variable.
+The properties are obtained from an `MDRunBase` object. The list of available properties is:
+velocity in $x, y, z$ `vel_x`, `vel_y`, `vel_z`; force in $x, y, z$ `force_x`, `force_y`, `force_z`;
+charge, and radius.
+
+!syntax parameters /AuxKernels/MDGranularPropertyAux
+
+!syntax inputs /AuxKernels/MDGranularPropertyAux
+
+!syntax children /AuxKernels/MDGranularPropertyAux
+
+!bibtex bibliography