MFIX2014-1 Release Announcement

Dear MFIX user,

We are pleased to announce the release of the new version of MFIX (MFIX2014-1). 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

MFIX Development Team

Changes from MFIX2013-2 (Date: 09/18/2013) to MFIX2014-1 (Date: 10/01/2014)

Some feature improvements are fairly aggressive and required major changes to the code. As a result, backward compatibility is not guaranteed for either input or restart files. Please contact the development team through the mailing list (See User Guide [1]) if you have difficulties running a previous model with the new release.

New features added:

  • Variable solids density
    • The material density of a solids phase changes as a result of chemical reactions (changing species composition) with the assumption that the solids volume fraction remains constant.
  • DEM Complex boundaries
    • The DEM/Cartesian cut-cell implementation was updated such that boundaries (walls) can be defined through STL files. This change allows for greater geometry complexity with better particle-wall collision detection.

Changes in existing features:

  • DEM code refactoring for better performance gave a 4x speedup compared to the Release 2013-2 (for tutorials/FluidBed_DES with 38,400 particles running in serial.)
  • DEM particle configuration is based on initial condition settings (e.g., IC_EP_s).
  • Cartesian grid cut-cell re-indexing method was implemented to re-order cells when a large number of inactive cells are generated. This provides a more efficient way of looping through computational cells which can substantially speedup the code execution for complex geometries.
  • The make_mfix build script was completely overhauled.
    • Build script was split into several files/scripts.
    • Build settings can be passed as build arguments.
    • Parallel-make build support.
    • Automatic Makefile generation at build time for dependency detection.
    • Each supported system and compiler has its own settings file allowing for easier modification and maintenance.
  • Improved checks for user input
    • Checks on solids model specifications are restricted to the solids model type so that unnecessary data is no longer needed. This improvement applies mainly to DEM and PIC solids models.
    • Error messages are consistently managed based on user input settings. If FULL_LOG is specified, error messages are written the LOG file and sent to std-out. Otherwise, error messages are only written to the LOG file.


  • Updated documents
    • Readme file renamed to MFIX User Guide [1]

Community Involvement:

    • Improved center-line treatment for cylindrical coordinate systems. Bakshi, A., Altantzis, C., Ghoniem, A.F. (2014). "Towards accurate three-dimensional simulation of dense multi-phase flows using cylindrical coordinates," Powder Technology, 264:242-255.
    • A shape dependent particle-fluid drag coefficient was used to create a tutorial for the new user defined drag functions (see mfix/tutorials/usr_drag).
    • Dioguardi, F., Dellino, P., Mele, D. (2014). "Integration of a new shape-dependent particle-fluid drag coefficient law in the multiphase Eulerian-Lagrangian code MFIX-DEM," Powder Technology, 260:68-77.


Project Metrics:

  • Change from 2013-2 Release:
    • 46 files and about 6,000 lines of code were added (net count)
  • 2014-1 Total count:
    • Files: 572
    • Lines: 211,825
    • Blank Lines: 32,272
    • Code Lines: 120,990
    • Comment Lines: 62,139
    • Statements: 87,625