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MFiX 20.2 Release Announcement

Dear MFiX user,

We are pleased to announce the MFiX 20.2 release. Please visit the download page to download the latest version. See the release note below that highlights the changes from the previous version.

Please visit the MFS forum for any software related questions, or send administrative questions to


The MFiX Development Team

New features:

  • PIC time step control through a PIC CFL (Courant-Friedrichs-Lewy) number. The user now has the option to specify a CFL number used to limit the PIC time step. There are three control parameters with this new capability:
    • PIC CFL : CFL number used to limit the PIC time step ( 0<PIC CFL<=1, leave blank to turn off PIC time step control).
    • Parcel fraction threshold: Threshold (fraction of total PIC parcels) above which the change in solids time step is invoked. Default value is 0.01 (i.e., time step is adjusted if more than 1% of the parcels CFL numbers are above the specified CFL number).
    • PIC control method: Solids time step will be based on either maximum or average calculated CFL.
  • Moving STL files for granular DEM: A new internal surface type can be used to flag an STL file as an internal surface. The user can then write a UDF to move the STL geometry during simulation. See the DEM 3D mixer tutorial.
  • Added cyclone tutorial showing how to use a closed STL file with inlet and outlet Boundaries flush with the MFiX box.
  • Improved version of GTSH kinetic theory model, including a new monodisperse Radial Distribution Function (RDF) by Ma & Ahmadi. The RDF must now be explicitly set in all TFM models using the 'RDF_TYPE' keyword.
  • Added History tab to view the list of changes made to the project .mfx file. The project version is now saved and displayed at run time.


  • When setting up a DEM simulation in the GUI, display an estimated particle count in each Initial Condition Region.
  • Added Option to unlock any MFiX keyword in the Advanced pane.
  • Added controls to define the solids time step factor (ratio of collision time to solids time step), and to remove rogue particles.
  • Added option to reset all meshing tolerances to their default values (Mesher pane).
  • Improved the "Remove keyword" dialog window to better handle invalid keywords.
  • Improved the rounding when using "AUTOSCALE" method to fit the geometry into the MFiX extents.
  • Remember the solver that was used in a previous simulation.
  • Changed two run settings: Increased the number of partitions in each direction to 9999 (NODESI, NODESJ, NODESK). Increase the default batch wallclok limit to 172,800 seconds (2 days).

Notable bug fixes:

  • Fixed Distributed I/O files and enable the GUI to visualize them.
  • Added DES user-defined variables in the list of variables that can be used in a monitor region.
  • Fixed monitors returning zero mass flow rates along West, South and Bottom planes.
  • Fixed segfault when particle species are defined with energy equation turned off.
  • Fixed New project filters.
  • Fixed Elapsed wall time displayed during a run.