GMS:SEAWAT Packages

SEAWAT specific packages include the Variable-Density Flow (VDF) and Viscosity (VSC) packages. The package dialogs for both packages are available under the SEAWAT menu. For the package menu items to be available, the packages must first be enabled from the SEAWAT Global Options Dialog. For a detailed description of the VDF and VSC input options, please refer to the SEAWAT manual.

VDF Package

The SEAWAT VDF Package dialog

The VDF package can be used in a SEAWAT simulation to model the affects of concentration on fluid density. The input values available in the VDF package include:

• IWTABLE – Active variable-density water table corrections. A flag used to activate the variable-density water-table corrections when turned on.
• MFNADVFD – Internodal density calculation method. A flag that determines the method for calculating the internodal density values used to conserve

fluid mass. Options include:

• • Central-in-space algorithm (eq. 2)
  • Upstream-weighted algorithm (ne. 2)
• DENSEMIN – Minimum fluid density.
• DENSEMAX – Maximum fluid density.
• FIRSTDT – Length of first transport time step.
• NSWTCPL – Flow/transport coupling.
• DNSCRIT – Convergence criteria.
• MT3DRHOFLG – type of fluid density calculation.
  • When equal to zero, the fluid density for each grid cell can be entered in the table at the bottom of the dialog. For INDENSE enter -1 to use values from previous stress period, 0 to use DENSREF, and 1 to enter values for DENSE column.
  • When equal to -1, the fluid density will be calculated using one or more species entered in the table at the bottom of the dialog using species ID, DRHODC, and CRHOREF. Rows can be entered into the table with the tool bar below the table.
  • When greater than or equal to 1 density is calculated using the corresponding species number.
• DENSREF – Reference fluid density.
• DRHODC – Density/concentration slope. The slope of the linear equation of state that relates fluid density to solute concentration.
• DRHODPRHD – Density/pressure slope.
• PRHDREF – Reference pressure head.

Species Table

This table allows adding or removing each solute species by using the Insert Row File:GMS - Insert Row icon.png or Delete Row File:GMS - Delete Row icon.png buttons. Options for the VDF package include:

• Species Name – The name will be based on the assigned Species ID.
• Species ID – The identity number of the species as assinged in the MT3D model.
• DRHODC – Density/concentration slope.
• CRHOREF – The reference concentration for species.

VSC Package

The SEAWAT VSC Package dialog

The VSC package can be used in a SEAWAT simulation to model the affects of concentration on fluid viscosity. Using the Viscosity Package requires using the VDF package and the LPF package in MODFLOW. The input values available in the VSC package include:

• VISCMIN – Minimum viscosity.
• VISCMAX – Maximum viscosity.
• MT3DMUFLG – Type of viscosity calculation.
  • When equal to zero, the fluid viscosity for each grid cell can be entered in the table at the bottom of the dialog. For INVISC enter -1 to use values from previous stress period, 0 to use VISCREF, and 1 to enter values for VISC column.
  • When equal to -1, the fluid density will be calculated using one or more species entered in the table at the bottom of the dialog using species ID, DMUDC, and CMUREF. Rows can be entered into the table with the tools bar below the table.
  • When greater than or equal to 1 viscosity is calculated using the corresponding species number.
• VISCREF – Reference viscosity.
• DMUDC – Viscosity/concentration slope.
• CMUREF – Reference concentration.
• MTMUTEMPSEC – Temperature species ID.
• AMUCOEFF – Coefficients for equation 18-20 in SEAWAT 4 documentation.

Species Table

This table allows adding or removing each solute species by using the Insert Row File:GMS - Insert Row icon.png or Delete Row File:GMS - Delete Row icon.png buttons. Options for the VSC package include:

• Species Name – The name will be based on the assigned Species ID.
• Species ID – The identity number of the species as assinged in the MT3D model.
• DMUDC – Viscosity/concentration slope.
• CMUREF – Reference concentration.