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MFIX2010-1 Release Announcement

Dear MFIX user,

We are pleased to announce the release of the new stable version of MFIX (MFIX2010-1). Please visit to download the latest version. Please see the attached release notes that highlight the changes from the previous version.

Please send any software related questions to or administrative questions

MFIX Development Team

Changes from MFIX2007-4 (Date: 12/31/2007) to MFIX2010-1 (Date: 02/02/2010)

Changes in existing features:

  • Bug fixes and enhancements:
    • Solids inventory reporting problem for parallel runs
    • Unit conversion from CGS to SI for dimensional quantities.
    • Print format changes to accommodate processor counts > 100
  • Enhancements:
    • Semi-implicit treatment of IA conductivity term
    • Conducted extensive debugging and verification of the DEM code
    • Updated DEM test cases
  • Updated documents:
    • Equations document [1]
    • Readme file [2]

New features added:

  • HYS polydisperse drag model and test case
    • The Holloway, Yin and Sundaresan (HYS) drag relation accounts for the effect of finite Reynolds number on the fluid-particle drag experienced by particles in polydisperse suspensions.
    • The HYS drag model is described in mfix/doc/HYS_drag.pdf.
  • DEM
    • Expanded DEM code so particles of differing size and density can be modeled (polydispersity).
    • Added a second order integration method (Adams Bashforth) to DEM as an option (DES_INTG_METHOD).
    • Added the Hertzian collision model to DEM as an option (DES_COLL_MODEL).
    • Created an updated user guide/document for the DEM code that includes a discussion on theory, numerics, and the verification tests [3]
  • Cartesian Grid cut cell technique
    • This new capability allows the definition of curved or sloping boundaries, instead of the usual stair-step representation.
    • Computational cells are truncated at the wall to conform to the shape of the boundaries.
    • The Cartesian grid technique is available for the Euler-Euler approach and includes no-slip and free-slip boundary conditions for either gas or solids phases.
    • A user guide describing the utilization of the cut cell technique is located in mfix/doc/Cartesian_grid_user_guide.pdf [4].
    • Some tutorials located at mfix/Cartesian_grid_tutorials illustrate the new capability.
  • Distributed I/O
  • Option to compile using gfortran

Under Development:

    • GHD (Garzo, Hrenya, and Dufty) granular kinetic theory
      • Code was updated with GHD granular kinetic theory and a simple shear flow case was added to tests/GHD to show how this model is used.
      • The major difference between this theory and previous KT's that it solves mixture momentum and granular energy equations instead of the individual solids phases equations.
      • Currently this theory is for granular flows (no fluid) and only simple wall BC can be applied (i.e. no slip, free slip)
      • The effect of fluid-solid drag was included in the GHD theory.
    • DEM
      • Adding inlet/outlet capabilities to DEM



  1. S. Benyahia, M. Syamlal, T.J. O'Brien, "Summary of MFIX Equations", From URL, August 2009.