Taking Advantage of the SRH-2D Channel Calculator

The Surface-water Modeling System (SMS) provides a useful tool that generates an estimated water surface elevation on an "Exit-H" boundary condition in an SRH-2D model. The Channel Calculator in SMS makes it easier to calculate water surface elevation values. It also gives you greater control of over the parameters

When building an SRH-2D model, the exit boundary will need to be defined. A constant elevation is often used, but this can not be sufficient in many cases. The Exit-H boundary condition is a stage type exit boundary where water surface elevation may be given as a constant number or as a stage-discharge or rating curve. The Channel Calculator is used to compute and assign a normal or critical water surface elevation for the outflow boundary condition. It also gives you greater control over the parameters used to determine the outflow conditions.

Example of the Channel Calculator in SMS

The Channel Calculator is accessed through the SRH2D Assign BC dialog. The Populate using Channel Calculator button appears at the bottom of the dialog when "Exit-H (subcritical outflow)" is selected as the BC Type and the Water Surface Elevation option has been determined.

The Channel Calculator specifies a composite roughness value, slope, and flow. SMS extracts a ground elevation cross section from a specified underlying elevation data source (mesh) that is used to compute the area and wetted perimeter. The calculator can make use of different types of elevation data sources which include DEMs, meshes, and scatter sets. Roughness and slope values will be required for the final calculation. Other options, such as the WSE offset, are optional and should only be used when necessary for your project.

The Channel Calculator will display a preview of the exit area cross section with normal and critical depth. When the Channel Calculator will save the values entered when exited. The values in the calculator can be changed later if needed.

The Channel Calculator in SMS gives you a useful tool for determining exit water-surface values for your SRH-2D projects. Try using it in SMS today!

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Moving Data to Other Geometries

After you have created a model in the Surface-water Modeling System (SMS), it is not uncommon to need to move your vector data or solution datasets from one geometry to another. It could be that your model ran using a 2D mesh and now you want to move the vector data to an unstructured grid for use in another simulation. SMS gives you the ability to accurately move vector data from one geometry to another which can significantly enhance the precision of your modeling efforts.

The Interpolate to UGrid tool is a powerful feature designed to streamline this process of moving datasets from one geometry to another. The Interpolate to UGrid tool is located in the Toolbox with the suite of dataset tools.

Example of the Interpolate to UGrid Tool in SMS

The Interpolate to UGrid tool facilitates the interpolation of a dataset associated with one geometry to another within the same project. While it primarily is meant to work with unstructured grids (UGrids), it can be used with other geometries such as 2D meshes or Cartesian grids. The tool will accept any dataset on the geometry, including vector and elevation sets.

The tool will follow an interpolation process to assign values on nodes or cells from one geometry to the next. Because of this, it is important to review the dataset after it has been moved, to verify that it transferred as expected.

The Interpolate to UGrid tool gives you several features that let you control the process of moving data from one geometry to another. These include:

  • Versatile Interpolation Methods: Choose the interpolation method that best suits your data and modeling objectives to achieve optimal results.
  • Customizable Interpolation Dimension: Tailor the interpolation process to match the dimensions of your target grid, whether it's 2D or 3D.
  • Truncation Options: Control the range of interpolated values with flexible truncation options. Whether you want to preserve the original data range or define custom minimum and maximum values, this tool provides the flexibility you need to fine-tune your results.
  • Extrapolation Capabilities: Handle extrapolation scenarios with ease, choosing from various extrapolation options to extend your dataset beyond the convex hull of the scatter point set.

Whether you're working with unstructured grids, 2D meshes, or other geometric entities, this tool provides the functionality and flexibility you need to enhance the accuracy of your modeling efforts. Make use of the Interpolate to UGrid tool in your SMS projects today!

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New Import and Export Curvilinear Grid Tools

There are two new tools in the Surface-water Modeling System 13.3 toolbox. If you work with curvilinear grids, then you’ll be pleased to know that there are now tools to import and export curvilinear grids. Both of these tools can be found in the Unstructured Grids folder in the toolbox.

Curvilinear grids are comprised of nodes organized into cells, which define the computational domain of a numerical model. Apart from defining the domain, these grids can also hold extra data like material properties for elements and boundary conditions for nodes. Curvilinear grids must be made up of only quadrilateral elements. This means that if you're creating a grid in SMS, you should make sure you're using the patch method for mesh generation.

Example of the Curvilinear Grid Tools in SMS

There are two file types that are supported for importing or exporting a curvilinear grid: CH3D (also referred to as GSMB) or EFDC (also referred to as LTFATE). Both file types include a cell i-coordinate and a cell j-coordinate dataset option. The EFDC file format includes additional input parameters for a depth dataset, Z roughness dataset, vegetation type dataset, and wind shelter dataset.

The Export Curvilinear Grid tool generates a curvilinear grid file (or files) for a curvilinear compatible mesh, scatter set, or UGrid within SMS. It can utilize user-provided I, J index datasets if available, and offers the capability to calculate I, J data indices. When computing these indices, the orientation of the initial cell on the surface determines the orientation of the grid's I, J axes.

You can use the Import Curvilinear Grid tool to import a pre-existing curvilinear (boundary fitted) grid into SMS as a UGrid object. This process simultaneously generates cell-based datasets that delineate the I, J indices for each cell within the UGrid. The exact format chosen and the nature of the data file(s) selected influence this import procedure.

Head over to SMS and give these new curvilinear grid tools a try!

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Tool to Fill a Hole in an Unstructure Grid

Have you ever found yourself working on a mesh in the Surface-water Modeling System (SMS) that has holes in places you don’t want them? Then you may want to check out the new Fill Holes in UGrid tool in the SMS toolbox. This tool can be a quick and easy way to fill in any undesirable voids in your 2D mesh or unstructured grid (UGrid).

Example of a UGrid before using the Fill UGrid tool

The Fill Holes in UGrid tool can be found in the SMS toolbox under the Unstructured Grids folder. From there, all you need to do is select the mesh or UGrid that has holes or voids you want filled from a dropdown list, give the new mesh a name, and run the tool. From there, SMS will create a duplicate of the input mesh, only now the mesh will have elements where the holes used to be.

Example of a UGrid after using the Fill UGrid tool

But what if you want to keep some of the voids in your mesh? That’s where the Extract Subgrid tool comes in handy. The Extract Subgrid tool can isolate a portion of a mesh, which is useful if the mesh is particularly large, or if you want to confine any changes to one specific area.

To create a subgrid, first you need to create an Area Property coverage with a polygon outlining the area you want to isolate. Then open the toolbox and find the Extract Subgrid tool, which is located in the Unstructured Grids folder. Select the mesh from the “Grid” dropdown, the coverage from the “Subgrid boundary coverage” dropdown, and enter a name for the new mesh. Now you can use the Fill Holes in UGrid tool to fill the voids in just the isolated portion of the mesh.

If you use the subgrid method to fill the voids in your mesh, there is one more tool you’ll want to know about: the Merge 2D UGrids tool. You can use this tool to merge the subgrid back with the original mesh. This tool is also in the toolbox under the Unstructured Grids folder. To use this tool, select the subgrid from the “Primary grid” dropdown, the original mesh from the “Secondary grid” dropdown, and choose a name for the new mesh.

The Fill Holes in UGrid, Extract Subgrid, and Merge 2D UGrids tools can help simplify and smooth the mesh editing process, no matter the project. Open SMS 13.3 and check out what these three tools can do for you today!

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