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MFIX2015-2 Release Announcement


Dear MFIX user,

We are pleased to announce the release of the new version of MFIX (MFIX2015-2). Please visit to download the latest version. Please see the release notes below that highlight the changes from the previous version.

Please send any software related questions to or administrative questions to

MFIX Development Team

Changes from MFIX 2015-1 (Date: 04/03/2014) to MFIX 2015-2 (Date: 10/27/2015)

New features added:

  • Autotools Build System - MFIX now uses autotools to configure and compile the code. This increases code portability while reducing overall script maintenance.
  • Semi-Explicit Coupling for DEM Simulation - A semi-explicit algorithm for coupled gas-solids flows was implemented in MFIX-DEM. This approach calculates gas-solids interaction forces during the gas phase time step resulting in decreased time to solution.
  • Two New Continuum Momentum Equation Formulations - MFIX's governing equations were not consistent with either of the primary recognized form of the governing equations.
    • The Jackson form of the governing equations contains the void fraction as a multiplier in front of the divergence of the gas phase stress tensor in the gas phase momentum equation and includes the solids volume fraction multiplied by the gas phase stress tensor in the solids phase momentum equation. Invoked using keyword Jackson.
    • The Ishii form of the governing equation includes the void fraction as a multiplier within the divergence term of the stress tensor. Invoked using keyword Ishii.



Changes in existing features:

  • Removed DES_CONTINUUM_COUPLED keyword - Pure granular flow simulations with MFIX-DEM and MFIX-PIC are now specified by setting the gas density to zero (RO_g0=0.0) making them consistent with MFIX-TFM. Coupled gas-solids simulation occur by specifying a non-zero or compressible gas phase density.
  • Removed DES_RES_DT and DES_SPX_DT - Pure granular flows simulations with MFIX-DEM and MFIX-PIC now use the same restart and data output keywords, RES_DT and SPX_DT. This makes specifying these values consistent across all models and simulation setups.



  • Updated documentation:
    • MFIX User Guide [1]


Project Metrics: 

  • Change from 2015-1 Release:
    • 20 fewer files and about 2,200 few lines of code
  • 2015-2 Total count:
    • Files: 540
    • Lines: 214,241
    • Blank Lines: 35,044
    • Code Lines: 121,693
    • Comment Lines: 60,700
    • Statements: 82,936