Flow Packages

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The flow related packages supported by ModelMuse are

•the Block-Centered Flow (BCF6) package,

•the Layer Property Flow (LPF) package,

•the Hydrogeologic Unit Flow (HUF2) package,

•the Upstream Weighting Package (UPW) package,

•the Node Property Flow package,

•the Storage package,

•the Ghost-Node Correction package,

•the Horizontal Flow Barrier (HFB) package,

•the Unsaturated Zone Flow (UZF) package for MODFLOW-2005,

•and the Seawater Intrusion package (SWI2).  

The first five packages are for simulating flow in the saturated zone. Only one of them can be used in any particular model. The Upstream Weighting package can only be used in MODFLOW-NWT. The Node Property Flow, Storage, and Ghost-Node Correction packages can only be used with MODFLOW 6. The Unsaturated-Zone Flow Package for MODFLOW 6 is treated as a boundary condition package rather than a flow related package.

The Block-Centered Flow package (BCF6) has four types of layers: (1) unconfined layers, (2) convertible layers with variable transmissivity, (3) convertible layers with constant transmissivity, and (4) confined layers. All aquifer properties are specified directly; there is not support for parameters. In confined layers and convertible layers with constant transmissivity, transmissivity is specified directly by the user rather than being calculated from hydraulic conductivity.

The Layer Property Flow (LPF) and Node Property Flow (NPF) packages have two types of layers: (1) convertible and (2) confined. (See the MODFLOW Layer Groups dialog box.) Aquifer properties can either be specified directly or through the use of parameters. However, in the LPF package some layers can be non-simulated.

In the Hydrogeologic Unit Flow package (HUF2), all aquifer properties are specified through parameters but the definitions of the aquifers is disconnected from the definition of the layers used in the model. Instead, the user specifies the top, bottom, and lateral extend of hydrogeologic units together with aquifer properties of these units and the package figures out how to combine them to assign appropriate properties to cells in the model. The Hydrogeologic Unit Flow package has two types of layers: (1) convertible and (2) confined. (See the MODFLOW Layer Groups dialog box.)

The Upstream Weighting package is nearly identical in its input to the Layer Property Flow package. However, it calculates the conductance between adjacent cells in a different way and is less prone to difficulties with cells converting between wet and dry. The differences are explained in the documentation for the Upstream Weighting package. The Upstream Weighting package is only available in MODFLOW-NWT.

The Horizontal Flow Barrier package (HFB) is used to simulate narrow barriers to horizontal flow. It does this by altering the conductance between pairs of adjacent cells in the same layer.

The Unsaturated Zone Flow package (UZF), as its name implies, simulates flow through the unsaturated zone.

The Seawater Intrusion package (SWI) is used for simulating variable density flow.

The Storage package is used to specify storage properties in transient MODFLOW 6 models.

The Ghost-Node Correction package is used to specify "ghost nodes" which are used to help correct for errors in flow calculation between cells in models in which cell centers are not aligned with each other. In ModelMuse, the Ghost-Node Correction package is only used with models with DISV grids. ModelMuse determines all the required ghost node locations and weights automatically.