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Online Guide to MODFLOW

Navigation: Groundwater Flow Process > Solvers

PCG - Preconditioned Conjugate-Gradient Package

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Abbreviation in Name file

PCG

Purpose

The Preconditioned Conjugate-Gradient package is used to solve the finite difference equations in each step of a MODFLOW stress period.

Documentation

Harbaugh, A.W., Banta, E.R., Hill, M.C., and McDonald, M.G., 2000, MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- User guide to modularization concepts and the Ground-Water Flow Process: U.S. Geological Survey Open-File Report 00-92, 121 p.

Harbaugh, A.W., 2005, MODFLOW-2005, the U.S. Geological Survey modular ground-water model -- the Ground-Water Flow Process: U.S. Geological Survey Techniques and Methods 6-A16. https://doi.org/10.3133/tm6A16

release.txt

ofr-00-92-errata.pdf

readme_PCG.txt

RevisedMF2005Input.pdf

Related Packages

Solvers

Supported in

MODFLOW-2000

MODFLOW-2005

MODFLOW-LGR

MODFLOW-CFP

MODFLOW-NWT

MODFLOW-OWHM

Other Notes

If the Lake package is used, more iterations may be required.

Input Instructions

Input to the Preconditioned Conjugate-Gradient (PCG) Package is read from the file that is type "PCG" in the name file. In MODFLOW-2000, all numeric variables are free format if the option “FREE” is specified in the Basic Package input file; otherwise, all the variables have 10-character fields. In MODFLOW-2005, all numeric variables are always free format.

FOR EACH SIMULATION

Data Set 0

[#Text]

Item 0 is optional—“#” must be in column 1. Item 0 can be repeated multiple times.

Data Set 1

MODFLOW-2000, MODFLOW-LGR, and MODFLOW-CFP:

MXITER ITER1 NPCOND

MODFLOW-2005, and MODFLOW-NWT, MODFLOW-OWHM

MXITER ITER1 NPCOND [IHCOFADD]

Data Set 2

MODFLOW-2000:

HCLOSE RCLOSE RELAX NBPOL  IPRPCG MUTPCG DAMP

MODFLOW-2005, MODFLOW-CFP, MODFLOW-NWT, and MODFLOW-LGR, MODFLOW-OWHM:

HCLOSE RCLOSE RELAX NBPOL  IPRPCG MUTPCG DAMPPCG [DAMPPCGT]

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