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Version 5.0 - Jan 2018
Visual MODFLOW Flex now supports SEAWAT (v4.00.05), a three-dimensional variable density flow and multi-species solute transport model developed by the USGS, based on a combination of MODFLOW and MT3D-MS. Version 4 of SEAWAT also supports viscosity effects and heat transport.
The following SEAWAT flow packages are supported in Visual MODFLOW Flex:
•BAS6 - Basic Package
•DIS - Discretization Package
•BCF6 - Block-Centered Flow Package LPF - Layer Property Flow Package
•HUF2 - Hydrogeologic Unit Flow Package (HUF2) OC - Output Control Package
•RCH - Recharge Package
•EVT - Evapotranspiration Package WEL - Well Package
•DRN - Drain Package RIV - River Package
•GHB - General-Head Boundary Package
•FHB - Flow and Head Boundary Package
•CHD - Time-Variant Constant Head Package
•LAK - Lake Package (LAK3)
•HFB6 - Horizontal Flow Barrier package (HFB6)
•OBS – Observation
•HOB - Hydraulic-Head Observation
•GMG - Geometric Multi-Grid Solver
•PCG - Pre-conditioned Conjugate Gradient Solver (PCG2)
•WHS - BiCGSTAB-P Matrix Solver
•LMG - Link Multi-Grid package for using the SAMG (Systems Algebraic Multi-Grid) Solver
The following SEAWAT transport packages are supported in Visual MODFLOW Flex:
•VDF - Variable Density Package
•VSC - Viscosity Package
•BTN - Basic Transport
•ADV – Advection
•DSP – Dispersion
•SSM - Source/Sink Mixing
•RCT – Reaction Package
•GCG - Generalized Conjugate Gradient Solver
NOTE: Advanced Translate/Run Settings (see below) enable partial support for simulating additional processes/packages (e.g. subsidence, drain return) developed outside of Flex.
Visual MODFLOW Flex now supports RT3D (v2.50), an advanced reactive transport engine based on the popular MT3DMS transport engine.
The following RT3D reaction modules are supported in Visual MODFLOW Flex:
•Instantaneous aerobic degradation of BTEX.
•Six Species, First-Order, Rate-Limited, BTEX Degradation using Sequential Electron Acceptors
•Double Monod Model
•Sequential First-Order Decay (up to 4 species, e.g., PCE/TCE/DCE/VC)
•Aerobic/Anaerobic PCE/TCE Dechlorination
•Cell Inspector: View and inspect structured and unstructured models at the cell-level using the new cell inspector, available in the workflow viewers. The cell inspector displays cell values for user-specified input and output data fields.
•Status Bar: Cell dimensions have been added to the status bar.
•Time-Picker: A time-picker is now available for unstructured grid workflow viewers.
•Layer-Picker: A layer-picker is now available for unstructured grid workflow viewers.
•Additional Translation/Run Settings: Added advanced settings for all supported engines (excluding MODFLOW-USG) so that you can specify whether individual packages are translated and/or run with the model, which provides the flexibility to integrate your own package input files within the Flex environment.
•Field Calculator: Populate boundary condition fields using a calculator that includes an expression builder dialog to facilitate the inclusion of variables based on your model’s properties (e.g. grid dimensions, elevations).
•Dispersion Parameters: Values can be edited in the Dispersion Parameter Dialog using copy, paste, and fill commands.
•Easy Classic Importing: Import your Classic project into Visual MODFLOW Flex directly from the file menu.
•Import Classic Concentrations: Boundary condition concentrations are now imported from Classic Projects.
•Animate Relative times in 3D views: in 3D View animations, the time stamp label for heads can be specified in relative or absolute time.
•Descriptive Title Bars for Settings Windows: settings windows now display descriptive window titles including the data layer and viewer settings to which they apply.
•Rename Objects: objects in the Data Explorer and most objects in the Model Explorer can be renamed.
•Feedback Button: added anonymous feedback buttons so that you can easily report what features you like or don’t like.
•SAMG Solver: added a single-processor version of the SAMG solver for Visual MODFLOW PRO users.
•Defining BCs along irregular polylines that are close to the active model limits produced unexpected results
•Reorder Tool was missing in some views
•The Show/Hide Gridlines button and associated toolbar disappeared intermittently from the viewer
•Well Data import failed without warning the user that the pumping schedule had inconsistencies, including pumping start date before model start date or pumping start date after pumping end date
•User could not assign polygon attribute data to conceptual recharge/evapotranspiration elements
•Problem(s) with Time Series Viewer
•Multiple PEST Workflows could be created for the same model run which corrupted the PEST workflow.
•Multiple issues in the advanced run/translation settings
•PCG Solver translation settings of the PCG2, PCG4, and PCG5 solver packages for MODFLOW-SURFACT models
The following issues may occur in Flex 5.0 under described/applicable conditions. Where available, a workaround is provided and/or fixes will be announced as they are available.
•When working with an extracted sub-grid model, whose parent model used a .HDS file as input for starting heads, the initial heads may not be correct. Workaround: extract the heads into surfaces and assign to the appropriate layer(s) 
•When adding more species, closing the project, and NOT saving the changes, newly added species are saved regardless. Workaround: delete unnecessary species from the project. 
•Unhelpful translation error "Vmac is running in the task bar, please close it and try again". Workaround: open Windows Task Manager, by right-clicking on the Windows Task Bar and close Vmac instance there. 
•Property and boundary condition zones may appear to be incorrect for child grids in 2D- or composite Viewers, particularly for the recharge and evapotranspiration packages. This is caused by the parent grid values being drawn on top of the child grid values in the viewer and parent grid properties are generally null within child grids. Workaround: reorder the layers. 
•Imported storage values from a Classic Project may have NAN values. Workaround: This issue may caused by a partially corrupted Classic File. If this occurs, temporarily remove the file called [Project Name].$STRG from the Classic Folder. This file may be located inside a sub-folder of the affected Classic project. Save it in another location while importing your project into Flex. The import of storage zones should proceed normally after doing this. Restore the file to its original location once the import is complete. 
•When importing pumping schedule date based on absolute time, Visual MODFLOW Flex fails to identify some time/date errors. Specifically, it does not record an error when the Pumping start date falls AFTER the pumping end date. Workaround: inspect dates in the Excel well file to be imported to verify that pumping starts on or after the model start date or import the well schedule using relative times. 
•In some scenarios (for instance if CHD cells are specified at the very bottom of the model [such as in the Henry model], the parallel version of SEAWAT may have convergence problems that cannot be resolved by changing solver parameters. Workaround: The 64-bit serial version of SEAWAT is free of this drawback and therefore is used by default in single model runs of SEAWAT in Flex. A fix for this issue will be announced and distributed as soon as it is available.
•In certain cases where grids have previously been generated, the grid refinement buttons in the View Finite Difference Grid step may not work following a subsequent model grid creation. Workaround: ensure that the grid is the active/turned on in the view (sometimes the conductivity grid is activated on top of or instead of the grid itself) 
•In certain cases, grid refinement may produce overly smoothed cell geometries. Workaround: The user may start with a finer grid and selectively coarsen to achieve the intended result or replace layer top/bottom elevations with conceptual horizons following grid refinement. A fix for this issue will be announced and distributed as soon as it is available. 
•Adding a transient boundary condition to a steady-state model where none previously existed and subsequently converting the model to transient may result in incorrectly translated time discretization (.DIS) and output control (.OC) input files. Workaround: The user may have to step out of and return to the Translate workflow step to force a refresh of the master schedule. 
For full version history, see the Visual MODFLOW Flex readme file at: https://www.waterloohydrogeologic.com/visual-modflow-flex-readme/