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MFiX 21.1 Release Announcement

We are pleased to announce the MFiX 21.1 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:

  • Six new drag laws were implemented:
    • Gao [1]
    • Sarkar [2]
    • Radl [3]
    • Tenneti, Garg, Subramaniam [4]
    • Difelice [5]
    • Difelice-Ganser [6]
  • Three new Nusselt number correlations were implemented:
    • Wakao [7]
    • Gunn [8]
    • Tavassoli [9]
  • Procedural geometry input: New geometry inputs for cylinders and bends offering better quality triangulated shapes than implicit or primitive shapes. See tutorial 3.10 "Procedural geometry" for a step-by-step-tutorial, or load the "procedural_geo" template (Main menu>New project from the GUI) to run.


  • Faster Thomas algorithm (37% faster in standalone benchmark, 22% faster within MFiX).
  • Recommending building the solver locally with "-march=native -O3" flag (10 to 20% faster run time was observed).
  • Updated convergence criteria near steady state (3 to 6x speedup for steady state single phase simulations were observed).
  • Additional settings for normalizing pressure correction and solids volume fraction residuals (PPG_DEN and EPP_DEN).
  • Additional setting to resize DEM buffer when running in parallel (DES_BUFFER_RESIZE_FACTOR).
  • Error popup windows catches full error text.

Notable bug fixes:

  • Fixed bug in the monitor settings causing error when deleting fluid species.
  • Fixed bug in the DEM Hertzian collision model that caused a division by zero when running in SMP.


[1] Gao, X., Li, T., Sarkar, A., Lu, L., Rogers, W.A., "Development and Validation of an Enhanced Filtered Drag Model for Simulating Gas-Solid Fluidization of Geldart A Particles in All Flow Regimes", Chemical Engineering Science, 184, 33-51, 2018.

[2] Sarkar, A., Milioli, F.E., Ozarkar, S., Li, T., Sun, X.,Sundaresan, S., "Filtered sub-grid constitutive models for fluidized gas-particle flows constructed from 3-D simulations", Chem. Eng. Sci., 152, 443-456, 2016.

[3] Radl, S., Sundaresan, S., "A drag model for filtered Euler-Lagrange simulations of clustered gas-particle suspensions", Chem. Eng. Sci., 117, 416-425, 2014.

[4] Tenneti, S., Garg, R., Subramaniam, S., "Drag law for monodisperse gas solid systems using particle-resolved direct numerical simulation of flow past fixed assemblies of spheres", Int. J. Multiph. Flow, 37(9), 1072-1092, 2011.

[5] R. Di Felice, "The voidage function for fluid-particle interaction systems", Int. J. Multiph. Flow 20 (1994) 153-159.

[6] G.H. Ganser, "A rational approach to drag prediction of spherical and nonspherical particles", Powder Technol. 77 (1993) 143-152.

[7] Wakao N, Kaguei S, Funazkri T., "Effect of fluid dispersion coefficients on particle-to-fluid heat transfer coefficients in packed beds: correlation of Nusselt numbers", Chemical engineering science. 1979;34(3):325-336.

[8] Gunn D., "Transfer of heat or mass to particles in fixed and fluidised beds", International Journal of Heat and Mass Transfer. 1978;21(4):467-476.

[9] Tavassoli H, Peters E, Kuipers J., "Direct numerical simulation of fluid particle heat transfer in fixed random arrays of non-spherical particles", Chemical Engineering Science. 2015;129:42-48.

Changes from 21.1.0 to 21.1.1

bug fixes

  • Fixed typo in TGS drag model label.
  • Fixed floating point exception in Gao drag law.
  • Fixed segfault in Srivastava and Sundaresan friction model.
  • Avoid overflow in linear solver matrix multiplication in DMP with interactive solver.
  • Use hyperthreading if available on local machine for DMP runs.

Changes from 21.1.1 to 21.1.3

Installation issues

  • Fixed VTK import error with the latest conda version (Windows and Linux).

Changes from 21.1.3 to 21.1.4

  •  Fixed JSON encoding error