8.3.1. Run Control

8.3.1.1. RUN_NAME

Data Type: CHARACTER

required

Name used to create output files. The name should generate legal file names after appending extensions. Ex: Given the input, RUN_NAME = “bub01”, MFIX will generate the output files: BUB01.LOG, BUB01.OUT, BUB01.RES, etc.

8.3.1.2. DESCRIPTION

Data Type: CHARACTER

Problem description. Limited to 60 characters.

8.3.1.3. UNITS

Data Type: CHARACTER

required

Simulation input/output units.

Table 8.2 Valid Values

Name

Default?

Description

cgs

All input and output in CGS units (g, cm, s, cal).

SI

All input and output in SI units (kg, m, s, J).

8.3.1.4. RUN_TYPE

Data Type: CHARACTER

required

Type of run.

Table 8.3 Valid Values

Name

Default?

Description

new

A new run. There should be no .RES, .SPx, .OUT, or .LOG files in the run directory.

RESTART_1

Traditional restart. The run continues from the last time the .RES file was updated and new data is added to the SPx files.

RESTART_2

Start a new run with initial conditions from a .RES file created from another run. No other data files (SPx) should be in the run directory.

8.3.1.5. TIME

Data Type: DOUBLE PRECISION

Simulation start time. This is typically zero.

8.3.1.6. TSTOP

Data Type: DOUBLE PRECISION

Simulation stop time.

8.3.1.7. OPTFLAG1

Data Type: DOUBLE PRECISION

Use nrel-cu optimization routines?.

8.3.1.8. DT

Data Type: DOUBLE PRECISION

Initial time step size. If left undefined, a steady-state calculation is performed.

8.3.1.9. DT_MAX

Data Type: DOUBLE PRECISION

Maximum time step size.

8.3.1.10. DT_MIN

Data Type: DOUBLE PRECISION

Minimum time step size.

8.3.1.11. DT_FAC

Data Type: DOUBLE PRECISION

Factor for adjusting time step.

  • The value must be less than or equal to 1.0.

  • A value of 1.0 keeps the time step constant which may help overcome initial non-convergence.

8.3.1.12. PERSISTENT_MODE

Data Type: LOGICAL

Force a forward time-step if the maximum number of iterations, MAX_NIT, is reached. The forward time-step is only forced after reaching the minimum time-step, DT_MIN, for adjustable time-step simulations (DT_FAC /= 1). This option should be used with caution as unconverged time-steps may lead to poor simulation results and/or additional convergence issues.

Table 8.4 Valid Values

Name

Default?

Description

.TRUE.

Force forward time-step when DT=DT_MIN and the maximum number of iterations are reached.

.FALSE.

Abort run when DT < DT_MIN.

8.3.1.13. AUTO_RESTART

Data Type: LOGICAL

Flag to restart the code when DT < DT_MIN.

8.3.1.14. MOMENTUM_X_EQ(PHASE)

Data Type: LOGICAL

  • \(0 \le Phase \le 10\)

Flag to enable/disable solving the X-momentum equations.

Table 8.5 Valid Values

Name

Default?

Description

.TRUE.

Solve X-momentum equations.

.FALSE.

The X velocity initial conditions persist throughout the simulation.

8.3.1.15. MOMENTUM_Y_EQ(PHASE)

Data Type: LOGICAL

  • \(0 \le Phase \le 10\)

Flag to enable/disable solving the Y-momentum equations.

Table 8.6 Valid Values

Name

Default?

Description

.TRUE.

Solve Y-momentum equations.

.FALSE.

The Y velocity initial conditions persist throughout the simulation.

8.3.1.16. MOMENTUM_Z_EQ(PHASE)

Data Type: LOGICAL

  • \(0 \le Phase \le 10\)

Flag to enable/disable solving the Z-momentum equations.

Table 8.7 Valid Values

Name

Default?

Description

.TRUE.

Solve Z-momentum equations.

.FALSE.

The Z velocity initial conditions persist throughout the simulation.

8.3.1.17. JACKSON

Data Type: LOGICAL

Flag to enable Jackson form of momentum equations. See Anderson and Jackson, (1967), IECF, 6(4), p.527.

Table 8.8 Valid Values

Name

Default?

Description

.TRUE.

Solve Jackson form of momentum equations.

.FALSE.

Default form.

8.3.1.18. ISHII

Data Type: LOGICAL

Flag to enable Ishii form of momentum equations. See Ishii, (1975), Thermo-fluid dynamic theory of two-phase flow.

Table 8.9 Valid Values

Name

Default?

Description

.TRUE.

Solve Ishii form of momentum equations.

.FALSE.

Default form.

8.3.1.19. ENERGY_EQ

Data Type: LOGICAL

Solve energy equations.

Table 8.10 Valid Values

Name

Default?

Description

.TRUE.

Solve energy equations.

.FALSE.

Do not solve energy equations.

8.3.1.20. SPECIES_EQ(PHASE)

Data Type: LOGICAL

  • \(0 \le Phase \le 10\)

Solve species transport equations.

Table 8.11 Valid Values

Name

Default?

Description

.TRUE.

Solve species equations.

.FALSE.

Do not solve species equations.

8.3.1.21. TURBULENCE_MODEL

Data Type: CHARACTER

Gas phase turbulence model. [“NONE”]

For K_EPSILON (K-epsilon turbulence model for single-phase flow):

  • Numerical parameters (like under-relaxation) are the same as the ones for SCALAR (index = 9).

  • All walls must be defined (NSW, FSW or PSW) in order to use standard wall functions. If a user does not specify a wall type, the simulation will not contain the typical turbulent profile in wall-bounded flows.

Table 8.12 Valid Values

Name

Default?

Description

NONE

No turbulence model

MIXING_LENGTH

Turbulent length scale must be specified for the full domain using keyword IC_L_SCALE.

K_EPSILON

K-epsilon turbulence model (for single-phase flow) using standard wall functions.

8.3.1.22. MU_GMAX

Data Type: DOUBLE PRECISION

Maximum value of the turbulent viscosity of the fluid, which must be defined if any turbulence model is used. A value MU_GMAX =1.E+03 is recommended. (see calc_mu_g.f)

8.3.1.23. DRAG_TYPE

Data Type: CHARACTER

Available gas-solids drag models. Note: The extension _PCF following the specified drag model indicates that the polydisperse correction factor is available. This option is available for TFM solids only. For PCF details see:

  • Van der Hoef MA, Beetstra R, Kuipers JAM. (2005) Journal of Fluid Mechanics.528:233-254.

  • Beetstra, R., van der Hoef, M. A., Kuipers, J.A.M. (2007). AIChE Journal, 53:489-501.

  • Erratum (2007), AIChE Journal, Volume 53:3020

Table 8.13 Valid Values

Name

Default?

Description

SYAM_OBRIEN

Syamlal M, OBrien TJ (1988). International Journal of Multiphase Flow 14:473-481. Two additional parameters may be specified: DRAG_C1, DRAG_D1

GIDASPOW

Ding J, Gidaspow D (1990). AIChE Journal 36:523-538

GIDASPOW_BLEND

Lathouwers D, Bellan J (2000). Proceedings of the 2000 U.S. DOE Hydrogen Program Review NREL/CP-570-28890.

WEN_YU

Wen CY, Yu YH (1966). Chemical Engineering Progress Symposium Series 62:100-111.

KOCH_HILL

Hill RJ, Koch DL, Ladd JC (2001). Journal of Fluid Mechanics, 448: 213-241. and 448:243-278.

BVK

Beetstra, van der Hoef, Kuipers (2007). Chemical Engineering Science 62:246-255

TPKKV

Tang, Peters, Kuipers, Kreibitzsch, & van der Hoef. AIChE J., 61(2), pp.688-698 (2015).

HYS

Yin, X, Sundaresan, S. (2009). AIChE Journal 55:1352-1368 This model has a lubrication cutoff distance, LAM_HYS, that can be specified.

USER_DRAG

Invoke user-defined drag law. (usr_drag.f)

GIDASPOW_PCF

(TFM only). see GIDASPOW

GIDASPOW_BLEND_PCF

(TFM only). see GIDASPOW_BLEND

WEN_YU_PCF

(TFM only). see WEN_YU

KOCH_HILL_PCF

(TFM only). see KOCH_HILL

8.3.1.24. DRAG_C1

Data Type: DOUBLE PRECISION

Quantity for calibrating Syamlal-O’Brien drag correlation using Umf data. This is determined using the Umf spreadsheet.

8.3.1.25. DRAG_D1

Data Type: DOUBLE PRECISION

Quantity for calibrating Syamlal-O’Brien drag correlation using Umf data. This is determined using the Umf spreadsheet.

8.3.1.26. LAM_HYS

Data Type: DOUBLE PRECISION

The lubrication cutoff distance for HYS drag model. In practice this number should be on the order of the mean free path of the gas for smooth particles, or the RMS roughness of a particle if they are rough (if particle roughness is larger than the mean free path).

8.3.1.27. SUBGRID_TYPE

Data Type: CHARACTER

Applies to Solids Model(s): TFM

Subgrid models.

Table 8.14 Valid Values

Name

Default?

Description

Igci

Igci, Y., Pannala, S., Benyahia, S., and Sundaresan S. (2012). Industrial & Engineering Chemistry Research, 2012, 51(4):2094-2103

Milioli

Milioli, C.C., Milioli, F. E., Holloway, W., Agrawal, K. and Sundaresan, S. (2013). AIChE Journal, 59:3265-3275.

8.3.1.28. FILTER_SIZE_RATIO

Data Type: DOUBLE PRECISION

Applies to Solids Model(s): TFM

Ratio of filter size to computational cell size.

8.3.1.29. SUBGRID_WALL

Data Type: LOGICAL

Applies to Solids Model(s): TFM

Flag for subgrid wall correction.

Table 8.15 Valid Values

Name

Default?

Description

.FALSE.

Do not include wall correction.

.TRUE.

Include subgrid wall correction.

8.3.1.30. MODEL_B

Data Type: LOGICAL

Shared gas-pressure formulation. See Syamlal, M. and Pannala, S. “Multiphase continuum formulation for gas-solids reacting flows,” chapter in Computational Gas-Solids Flows and Reacting Systems: Theory, Methods and Practice, S. Pannala, M. Syamlal and T.J. O’Brien (editors), IGI Global, Hershey, PA, 2011.

Table 8.16 Valid Values

Name

Default?

Description

.FALSE.

Use Model A. See J.X. Bouillard and R.W. Lyczkowski (1991), Powder Tech, 68:31-51.

.TRUE.

Use Model B. See Bouillard, J.X., Lyczkowski, R.W., Folga, S., Gidaspow, D., Berry, G.F. (1989). Canadian Journal of Chemical Engineering 67:218-229.

8.3.1.31. NSCALAR

Data Type: INTEGER

The number of user-defined scalar transport equations

to solve.

8.3.1.32. PHASE4SCALAR(SCALAR EQUATION)

Data Type: INTEGER

  • \(1 \le Scalar Equation \le 100\)

The phase convecting the indexed scalar transport equation.

8.3.1.33. PPO

Data Type: LOGICAL

Flag to run the pre-processing (mesh generation) only and exit.