Aquaveo & Water Resources Engineering News

Some of the more notable things completed by the GMS team during the month.

• Progress on database dialog
• Text export for MODFLOW-USG DISU, GNC, CLN, SWI
• PATH3DU progress
• Raster -> UGrid points
• Clip to bounds for Raster -> Scatter and Raster -> UGrid points
• TOUGH2 export improved
• UGrid point creation
• New class for getting UGrid interpolation points
• UGrid cell refinement
• Map -> UGrid with nested grids
• Good refactoring / modernization

Some of the more notable things completed by the GMS team during the month.

• Fixed 5 bugs
• Added interface in Preferences dialog to access default text viewer settings
• UGrid points can now be contoured (colored) according to their data values similar to scatter points
• Zoom To Extents command for CAD layers added
• GMS can now import MODFLOW-USG files written by GMS that aren't part of the project
• UGrid cell centers can now be displayed
• Various work on updating the wiki
• Added option to Display Options dialog to show all options, not just those for existing data
• Refined dragging in the Project Explorer so that items could be dragged to the top of the list without dropping on the parent
• Vector xyz dataset info for selected UGrid cells now displayed in status bar
• TOUGH2 MESH file export from UGrids added
• Print layout tools designed

The next version of GMS (10.1) will include the ability to export TOUGH2 MESH files. Users will be able to build complex 3D UGrids using all the tools available in GMS and use those UGrids in their TOUGH2 models. Voronoi grids, triangular grids, grids created from horizons and solids - all will be exportable. This feature is implemented in our development branch but needs more test cases. If you would like to help us test this feature, please send an email to mkennard@aquaveo.com.

The GMS team just added support for the ghost node correction (GNC) package in GMS. This will be available in GMS 10.1. A wiki page has already been created to document the interface.

The GNC package can be used to improve the accuracy of a model in which there are grid cells that do not follow the assumptions of the finite volume method - namely that the line connecting the center points of adjacent cells is also a perpendicular bisector of the face between the cells. This situation arises with quadtree, octree, and nested type grids, as well as with many other types of grids. Regular (quadrilateral) grids and voronoi grids do not have this issue. All of these types of grids can easily be created in GMS.

¹

GMS can calculate all the ghost node data automatically, or the user can enter the data manually. When done automatically, GMS uses an algorithm developed with input from Sorab Panday (author of MODFLOW-USG). The algorithm is illustrated in the following figure:

Ghost node locations are calculated using the perpendicular bisector of the face between adjacent cells and its intersection with the lines connecting cell centers. AlphaJ values are calculated based on the distances from the ghost nodes to the adjacent cells. A new tutorial was created to teach how to use the new GNC functionality in GMS. The GNC package typically increases the accuracy of a model by a small amount and is therefore often unnecessary.

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^{1. Panday, Sorab, Langevin, C.D., Niswonger, R.G., Ibaraki, Motomu, and Hughes, J.D., (2013), MODFLOW-USG, version 1: An unstructured grid version of MODFLOW for simulating groundwater flow and tightly coupled processes using a control volume finite-difference formulation: U.S. Geological Survey Techniques and Methods, book 6, chap. A45, 66 p., Reston, Virginia↩}