4.1. Model setup

The Model pane is used to specify global project settings. Depending on what is selected, other panes are enabled or disabled.

  • Description allows for a short model description to be provided. This is written in the .OUT file by the solver.

  • Solver specifies the model solver.

    • Single-phase is the MFiX fluid solver. This disables all solids model inputs.

    • Two-Fluid Model (MFiX-TFM) treats both the fluid and solids as interpenetrating continua.

    • Discrete Element Model (MFiX-DEM) treats the fluid as a continuum while modeling individual particles as spheres and collisions.

    • Coarse-grained Particle Model (MFiX-CGP) treats the fluid as a continuum while using single spheres and collisions to represent groups of real particles with similar physical characteristics.

    • Superquadric Particle Model (MFiX-SQP) treats the fluid as a continuum while modeling individual particles using superquadrics and collisions. Superquadrics allow for modeling non-spherical particles.

    • Glued-sphere Particle Model (MFiX-GSP) treats the fluid as a continuum while “gluing” DEM particles to each other to approximate the behavior of non-spherical particles.

    • Particle in Cell Model (MFiX-PIC) treats the fluid as a continuum while using “parcels” to represent groups of real particles with similar physical characteristics.

  • Disable the fluid phase turns off the fluid solver for MFiX-TFM and MFiX-DEM simulations for pure granular flows. The fluid solver cannot be disabled for single-phase flows.

  • Enable thermal energy equations solves thermal transport equations for all phases.

  • Turbulence Model incorporates the selected turbulence model.

    • None - Do not include turbulence.

    • L-Scale Mixing - Algebraic (zero-equation) turbulence model.

      • Requires a turbulent length scale definition for all initial condition regions.

    • K-Epsilon - Two-equation turbulence model (turbulent kinetic energy and turbulent dissipation rate).

      • Requires turbulent kinetic energy and turbulent dissipation definitions for all initial condition regions and all mass and pressure inflow boundary conditions.

  • Max turbulent viscosity has units of \((Pa \cdot sec)\) and is used to bound turbulent viscosity.

  • Gravity has units of \(({m}/{sec^2})\) and defines gravitational acceleration in the x, y, and z directions.

  • Drag model specifies the fluid-particle drag model. This option is only available with the MFiX-TFM and MFiX-DEM solvers.

    • Syamlal-O’Brien [SB1988]

      • Requires the specification of the C1 tuning parameter, 0.8 by default.

      • Requires the specification of the D1 tuning parameter, 2.65 by default.

    • Beestra-van der Hoef-Kuipers [BVK2007]

    • Gidaspow [DG1990]

    • Gidaspow Blend [LB2000]

    • Holloway-Yin-Sundaresan [HYS2010]

      • Requires the specification of the lubrication cutoff distance, 1e-6 meters by default.

    • Koch-Hill [HKL2001]

    • Wen-Yu [WY1966]

    • User-Defined Function (UDF)

      • A custom drag model must be provided in the usr_drag.f file

      • A custom solver must be built.

Note

The polydisperse tag following a specified drag model indicates that the polydisperse correction factor is available. For additional details see [HBK2005], [BVK2007a], and [BVK2007b].

Other advanced options that can be selected include:

  • Momentum formulation (Model A, Model B, Jackson, or Ishii)

    • Model A

    • Model B

    • Jackson

    • Ishii

  • Select sub-grid model

  • Sub-grid filter size

  • Sub-grid wall correction

Note

There are some restrictions to when using sub-grid models. They are only available with MFiX-TFM simulations using the Wen-Yu drag law, and without turbulence model. Additional restrictions apply.

[SB1988]

Syamlal, M, and O’Brien, T.J. (1988). Simulation of granular layer inversion in liquid fluidized beds, International Journal of Multiphase Flow, Volume 14, Issue 4, Pages 473-481, https://doi.org/10.1016/0301-9322(88)90023-7.

[HKL2001]

Hill, R., Koch, D., and Ladd, A. (2001). Moderate-Reynolds-number flows in ordered and random arrays of spheres. Journal of Fluid Mechanics, Volume 448, Pages 243-278. https://doi.org/10.1017/S0022112001005936

[DG1990]

Ding, J. and Gidaspow, D. (1990). A bubbling fluidization model using kinetic theory of granular flow, AIChE Journal, Volume 36, Issue 4, Pages 523-538, https://doi.org/10.1002/aic.690360404

[LB2000]

Lathouwers, D. and Bellan J. (2000). Modeling of dense gas-solid reactive mixtures applied to biomass pyrolysis in a fluidized bed, Proceedings of the 2000 U.S. DOE Hydrogen Program Review, https://www.nrel.gov/docs/fy01osti/28890.pdf

[WY1966]

Wen C.Y., and Yu Y.H. (1966). Mechanics of fluidization, The Chemical Engineering Progress Symposium Series, Volume 62, Pages 100-111.

[BVK2007]

Beetstra, R., van der Hoef, M.A., and Kuipers, J.A.M. (2007). Numerical study of segregation using a new drag force correlation for polydisperse systems derived from lattice-Boltzmann simulations, Chemical Engineering Science, Volume 62, Issues 1–2, Pages 246-255. https://doi.org/10.1016/j.ces.2006.08.054.

[HYS2010]

Holloway, W., Yin, X., and Sundaresan, S. (2010). Fluid‐particle drag in inertial polydisperse gas–solid suspensions, AIChE Journal, Volume 56, Issue 8, Pages 1995-2004. https://doi.org/10.1002/aic.12127

[HBK2005]

Hoef, M., Beetstra, R., and Kuipers, J. (2005). Lattice-Boltzmann simulations of low-Reynolds-number flow past mono- and bidisperse arrays of spheres: Results for the permeability and drag force. Journal of Fluid Mechanics, Volume 528, Pages 233-254. https://doi.org/10.1017/S0022112004003295

[BVK2007a]

Beetstra, R. , van der Hoef, M. A. and Kuipers, J. A. (2007), Drag force of intermediate Reynolds number flow past mono‐ and bidisperse arrays of spheres. AIChE J., 53: 489-501. https://doi.org/10.1002/aic.11065

[BVK2007b]

(2007), Erratum. AIChE J., 53: 3020-3020. https://doi.org/10.1002/aic.11330

[IPBS2012]

Igci, Y., Pannala, S., Benyahia, S., and Sundaresan, S. (2012). Validation studies on filtered model equations for gas-particle flows in risers, Industrial & Engineering Chemistry Research, Volume 54, Issue 4, Pages 2094-2103. https://doi.org/10.1021/ie2007278

[MMHAS2013]

Milioli, C.C., Milioli, F.E., Holloway, W., Agrawal, K. and Sundaresan, S. (2013), Filtered two‐fluid models of fluidized gas‐particle flows: New constitutive relations. AIChE J., Volume 59, Issue 9, Pages 3265-3275. https://doi.org/10.1002/aic.14130