MNW1: Multi-Node Well Package (Version 1) Pane

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The Multi-Node Well (version 1) package simulates wells whose open intervals extend beyond a single model cell. The pane for this package is on the MODFLOW Packages and Programs dialog box under Head Dependant Flux.

In addition to comments that will be printed at the beginning of the MNW1 input file, the user can specify several variables that are used in MNW1.

The MNW 1 package will use up to NOMOITER iterations to calculate the head and flow in a multinode well.

LOSSTYPE: identifies the model of well loss to be used. There are three options, "Skin," "Linear" and "Nonlinear."

If you choose "Nonlinear," you can specify a loss exponent (PLossMNW).

The flow between the the well and the cell is defined by the following equation.

Qn = (hWELL - hn)CWCn

Qn

is flow between the nth cell and the well (L3 / T).

hWELL

is the head in the well (L).

hn

is the head in the nth cell (L).

CWCn

is the nth cell-to-well conductance (L2 / T), which can be specified directly by the user or defined by: CWC = (A + B + CQnP-1)-1.

A

is a function of the well radius, the cell size and the transmissivity (T / L2).

B

is linear well-loss coefficient (T / L2). It is a function of a skin factor and the transmissivity

C

is nonlinear well-loss coefficient (TP / L(3P-1)), and

P

is power of the nonlinear discharge component of well loss that usually varies between 1.5 and 3.5 (Rorabaugh, 1953)

For each multinode well, the user either specifies CWC directly (usually for a horizontal well), or specifies the well radius and the skin factor. If the non-linear option is chosen, the user will also specifies the nonlinear well-loss coefficient for each multinode well. The exponent (P) is specified here as PLossMNW.

There are three output files that can be generated by MNW1:

•an input file for the well package which can be used in post-processing programs such as MODPATH.

•Water-level, discharge, and water-quality information for plotting time series for each cell in each multinode well.

•Water-level, discharge, and water-quality information for plotting time series for each multinode well taken as a whole.

For the latter two files, the data can be printed either at every time step or only when other data are printed as specified in the Output Control file.