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MFiX 19.1 Release Announcement

Dear MFiX user,

We are pleased to announce the MFiX 19.1 release. Please visit 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:

  • New implementation of the Particle in Cell (PIC) model: New and improved PIC model provides a good compromise between speed and accuracy for large scale simulations. The new PIC model includes:
    • Hydrodynamics
    • Heat transfer
    • Chemistry
    • Serial and parallel run
  • Ability to view STL normals and flip normal from the GUI
  • Ability to save image stack for animations
  • Quickly parse through the solver output to view Error/Warning/Info messages
  • PGI compiler support (non interactive solver)
  • Gridengine job submission script
  • Bug report (zip file) can be saved from GUI
  • Ability to read several non-overlapping STL files to generate the geometry.
  • Addition of implicit function buttons to the modeler toolbar
  • Log files: Ability to save Solid inventory, solver output, DT and NIT to files
  • Ability to plot Cp vs. Temperature for each species
  • Mass inflow BCs can overlap
  • User guide in PDF format


  • Better formatting of the .mfx file with output templates
  • VTK window: Better visibility controls for Cell and Particle data, additional color maps, Additional controls for the legend and time display, show number of particles/parcels
  • Scalar pane: Better controls for scalar equations
  • Mixed wall BCs (NSW, PSW or FSW can now be set independently for each phase)
  • Format .vtu filename indices without leading zeroes for index > 10000
  • Ability to turn on/off nrel_cu-optimization (default is off)
  • Improved data checks
  • Rewrite or refactoring of set_bc_flow, calc_grbdry, calc_s_ddot_s
  • When reading particle_input.dat, set phase index based on absolute and relative error

Notable bug fixes:

  • VTK directory creation: The solver would sometime crash while creating VTK subdirectories.
  • Cyclic BCs: Bug in MPI routine that didn’t work in serial
  • k-epsilon segfault: set wall function to one in cells where viscosity is zero)
  • Fix for explicitly coupled DEM simulations with stiff chemistry solver
  • Fix for DEM simulations with stiff chemistry solver: The fluid solver need not calculate particles rates when calculating other interphase transfer terms
  • Update one over moment of inertia when particle mass or radius changes
  • Solver sometimes failed when rotating restart files
  • Bug fixes in calc_k_cp especially for savage=1
  • When wrapping all BC extents in STLs, facets were sometimes created in bad locations
  • Fix for cohesive model that was counting edge interaction multiple times