run doc_scanner, update undocumented-keys

sufficiently coarsenable for good multigrid performance.

There is one more default behavior to be aware of.  There is a boolean :cpp:`refine_grid_layout`

that defaults to true but can be over-ridden at run-time.

that defaults to true but can be overridden at runtime.

If :cpp:`refine_grid_layout` is true and the number of grids created is less than the number of processors

(Ngrids < Nprocs), then grids will be further subdivided until Ngrids >= Nprocs.

Caveat: if subdividing the grids to achieve Ngrids >= Nprocs would violate the

:cpp:`blocking_factor` criterion then additional grids are not created and the

number of grids will remain less than the number of processors

number of grids will remain less than the number of processors.

Note that :cpp:`n_cell` must be given as three separate integers, one for each coordinate direction.

#. Next, if :cpp:`refine_grid_layout = true` and there are more processors than grids

   at this level, then the grids at this level are further divided until Ngrids >= Nprocs

   (unless doing so would violate the :cpp:`blocking_factor` criterion).

.. _Chap:QB:biseg:

Bidisperse Segregation 

Bidisperse segregation

======================

In this simple test conducted at NETL, a uniform, random mixture

defluidize. In the final state, the ceramic particles are essentially static

with a fluidized layer of nylon particles floating on top, in contrast to the

experiment, in which the full bed showed signs of fluidization. Investigation

into the over-segregation in this case is on-going. 

into the oversegregation in this case is ongoing.

.. figure:: figs/netl_biseg_1908_small.png

   Comparison of experiment and MFIX-Exa simulaton for rapid segregation

   of a bi-disperse particle mixture.

|                        | will be generated in that cell                    |        |         |

+------------------------+---------------------------------------------------+--------+---------+

| eps_overflow           | An artifact, like a knob, for the user to force   | Real   | 1.0     |

|                        | over-production (if value > 1), or                |        |         |

|                        | under-production (if value < 1) of DEM particles  |        |         |

|                        | overproduction (if value > 1), or                 |        |         |

|                        | underproduction (if value < 1) of DEM particles   |        |         |

+------------------------+---------------------------------------------------+--------+---------+

| small_volfrac          | This input gives the possibility to set a small   | Real   | 0.      |

|                        | volfrac value just for the DEM refined case,      |        |         |

+=====================+=======================================================================+=============+===========+

| plt_regtest         | Plot all variables (overrides all other plot flags).                  |    Int      | 0         |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

| plt_cp_g            | Plot fluid specific heat.                                             |    Int      | 0         |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

| plt_cp_gk           | Plot specific heat for each fluid species.                            |    Int      | 0         |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

| plt_drag_p          | Plot particle drag force.                                             |    Int      | 0         |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

| plt_ep_g            | Plot fluid volume fraction.                                           |    Int      | 1         |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

| plt_gradp_g         | Plot fluid pressure gradient.                                         |    Int      | 0         |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

| plt_h_g             | Plot fluid enthalpy.                                                  |    Int      | 0         |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

| plt_mu_g            | Plot fluid molecular viscosity.                                       |    Int      | 0         |

+---------------------+-----------------------------------------------------------------------+-------------+-----------+

| plt_omega_p         | Plot particle angular velocity.                                       |    Int      | 0         |

.. _inputs_mesh_ex:

.. code-block:: bash

   :caption: Snippet of intpus for mesh example. This is not a complete input file.

   :caption: Snippet of inptus for mesh example. This is not a complete input file.

   # Define periodicity and domain extents

   # -------------------------------------------------------------