.. _model_setup:

.. include:: /icons.rst

===========
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 :math:`(Pa \cdot sec)` and
   is used to bound turbulent viscosity.

-------

-  **Gravity** has units of :math:`({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

   -  *None*
   -  *Igci* [IPBS2012]_
   -  *Milioli* [MMHAS2013]_

-  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