GMS:GMG Package: Difference between revisions

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* ''Maximum outer iterations (MAXITER)'' – Also referred to as MXITER. For linear problems, set to 1. For nonlinear problems, set to a higher number though it is usually unnecessary to go above 100.
* ''Maximum outer iterations (MAXITER)'' – Also referred to as MXITER. For linear problems, set to 1. For nonlinear problems, set to a higher number though it is usually unnecessary to go above 100.
* ''Damping parameter (DAMP)'' – A value of 1.0 should be used for linear problems. For nonlinear problems, a value less than 1.0 but greater than 0.0 may be necessary to achieve convergence.
* ''Damping parameter (DAMP)'' – A value of 1.0 should be used for linear problems. For nonlinear problems, a value less than 1.0 but greater than 0.0 may be necessary to achieve convergence.
* Damping option (IADAMP)
* ''Damping option (IADAMP)'' – Flag that controls adaptive damping. Contains the following options:
** "(0) Constant"
** "(1) Cooley adaptive"
** "(2) RRR adaptive" 
* Maximum damping (DUP)
* Maximum damping (DUP)
* Minimum damping (DLOW)
* Minimum damping (DLOW)

Revision as of 14:43, 6 July 2016

MODFLOW
Pre-processing
MODFLOW Commands
Building a MODFLOW Model
Map to MODFLOW
Calibration
Packages Supported in GMS
Saving a MODFLOW Simulation
Importing MODFLOW Files
Unsupported MODFLOW Features
Run MODFLOW
Post-processing
MODFLOW Display Options
MODFLOW Post-Processing Viewing Options
Reading a MODFLOW Simulation
Tutorials
Packages
Flow: BCF6, HUF, LPF, UPW
Solvers:

DE4, GMG, NWT, PCG,

PCGN, LMG, SIP, SOR,

SMS
Other:

BAS6, BFH, CHD1, CLN,

DRN1, DRT1, EVT1, ETS1,

GAGE, GHB1, GNC, HFB1,

HUF, LAK3, MNW1, MNW2,

OUT1, RCH1, RIV1, SFR2,

STR1, SUB1, SWI2, WEL1,

UZF1
v • e

The GMG package is one of the solver packages for MODFLOW supported by GMS. The GMG solver is an iterative solver based on a multi-grid approach.

Parameters include:

  • Inner convergence residual (RCLOSE) – The algorithm computes the l2-norm of the residual and compares it against RCLOSE.
  • Maximum inner iterations (IITER) – For each linear solution. The default is 100. Specify a smaller number for nonlinear problems to prevent an excessive number of inner iterations.
  • Outer convergence residual (HCLOSE) – For nonlinear problems. After each linear solve (inner iteration), the maximum norm of the head change is compared against HCLOSE. Can be set to a large number for linear problems. Ignored if Maximum outer iterations is 1.
  • Maximum outer iterations (MAXITER) – Also referred to as MXITER. For linear problems, set to 1. For nonlinear problems, set to a higher number though it is usually unnecessary to go above 100.
  • Damping parameter (DAMP) – A value of 1.0 should be used for linear problems. For nonlinear problems, a value less than 1.0 but greater than 0.0 may be necessary to achieve convergence.
  • Damping option (IADAMP) – Flag that controls adaptive damping. Contains the following options:
    • "(0) Constant"
    • "(1) Cooley adaptive"
    • "(2) RRR adaptive"
  • Maximum damping (DUP)
  • Minimum damping (DLOW)
  • Maximum head change (CHGLIMIT)
  • Output flag (IOUTGMG)
  • Maximum head output (IUNITMHC)
  • Multi-grid preconditioner smoothing (ISM)
  • Multi-grid preconditioner coarsening (ISC)
  • Relocation parameter (RELAX)

For more info on the GMG solver look at the following document:

Wilson, John D., and Richard L. Naff. MODFLOW-2000, The US Geological Survey Modular Ground-Water Model--GMG Linear Equation Solver Package Documentation. No. 2004-1261. 2004. [1]
The MODFLOW GMG Solver package dialog.


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