SMS

Using a 2D UGrid with SRH-2D

By aquaveo on September 21, 2022

A 2D mesh in SMS has long been the standard geometry for SRH-2D simulations. However, you might have noticed in more recent versions of SMS that SRH-2D simulations can also use 2D unstructured grids (UGrids). Today, we examine what using a 2D UGrid can mean for SMS users who model SRH-2D simulations.

Being able to use a UGrid offers a couple advantages. For one, 2D UGrids don't require the SRH-2D Post-Processor because, unlike 2D meshes, they are already centroid-based. This means the SRH-2D results can be read directly onto the 2D UGrid. Additionally, the same SRH-2D model can be run with a mesh and then run with a 2D UGrid. Since the two geometries differ in how they store data, this practice might be helpful in troubleshooting issues with the geometry design for your model. In most cases where the mesh is well built, there should not be significant differences between the results you get from a UGrid-based SRH-2D simulation and a mesh-based simulation.

The steps for creating a 2D UGrid for an SRH-2D simulation are essentially the same as creating a 2D mesh:

Build a mesh generation coverage with polygons.
Specify what kind of grid-like structure you want in each.
Instead of converting the coverage to a 2D mesh, convert it to a 2D UGrid.

An already-existing 2D mesh can also be converted to a 2D UGrid if so desired.

Example of the 2D Mesh Polygon Properties dialog being used for UGrid or mesh generation

It's important to note that there are not yet any manual tools for editing 2D UGrids, so any desired adjustments to a 2D UGrid should be made before the UGrid is generated. As with the 2D mesh, this can be done by double-clicking in the polygons in the mesh generation coverage and using the dialogs that appear.

Furthermore, the principles for creating a quality mesh apply to creating a quality 2D UGrid. The quality of a UGrid is just as important to the model outcome as the quality of a mesh. In 2D UGrids for SRH-2D simulations, please keep in mind the following:

The elements should transition gradually from large to small and vice versa. Adjacent elements should not have enormous variations in size.
Areas that need more refined results should have finer quality elements.
For areas that use the patch option, the elements should be fairly even.
Triangular elements should not be excessively narrow.

These are only some of the considerations.

Much of this can be avoided by making sure that the mesh generator coverage is designed correctly. Again, adjustments to the 2D UGrid can really only be made in the mesh generator coverage before the UGrid has actually been generated.

Try using 2D UGrids in an SRH-2D simulation in SMS today!

Blog tags:

SMS

The Create Bridge Footprint Tool in SMS 13.2

By aquaveo on August 31, 2022

Do you have an SMS project with a bridge represented in the mesh? SMS 13.2 offers a new tool called Create Bridge Footprint that assists in representing bridge footprints in SRH-2D simulations.

Since the real-life effects of bridges can be complex, creating a mesh to represent them is often challenging. Modeling piers and abutments using older methods in SMS requires many polygons in Mesh Generation coverages. Now, the Create Bridge Footprint tool provides an alternative approach to creating an unstructured mesh under and around a bridge structure. Note that this tool replaces the functionality made available in the Bridge-Piers coverage, which you might have been using in SMS 13.1. However, many of the same settings are incorporated in this tool as well.

The Create Bridge Footprint tool, located in the Toolbox dialog, produces a coverage and mesh that represent the bridge footprint. These features can then be used to create a mesh that incorporates the bridge footprint into the larger mesh for the model.

Example of the Create Bridge Footprint Tool

The set up for the tool includes creating a new coverage with arcs that define the new bridge:

The first arc should define the centerline of the bridge. It is the longest arc.
Other arcs, drawn across the first arc, define where the piers and abutments are located. The length of the piers is set in the tool parameters before the tool is run, so the length of these arcs is unimportant.

When drawing the feature arcs to represent the bridge for the tool, there are some important things to keep in mind. One of them is that the bridge feature arcs must be the only feature objects in the coverage. Any other objects will confuse the Create Bridge Footprint tool.

It's also important to make sure that all of the shorter arcs cross the centerline, but none of them should intersect the centerline. In this case, intersecting is different from crossing in that it creates a node on both arcs. This splits the centerline arc, making it impossible for the tool to interpret the intended meaning of the arcs.

After setting up the arcs, there are some parameters to set in the tool to complete the model of the bridge. Then the tool can be run and the resulting mesh and coverage reviewed, and you're one step closer to completing your model.

Try the Create Bridge Footprint tool in SMS 13.2 today!

Blog tags:

SMS

Tips for Modeling 3D Bridges in SMS 13.2

By aquaveo on August 17, 2022

Do you have an SMS 13.2 project that could benefit from using a 3D bridge? Today's blog post covers some things to consider as you model 3D bridges in SMS.

First, it’s important to know that SMS identifies the arc drawn first as the upstream side of the bridge. So the order in which the arcs are drawn affects the final bridge model. However, before the bridge is fully created, it’s possible to switch which side of the bridge is upstream using the Swap Arcs command in the Bridge dialog. Checking that the arcs are assigned to the correct side of the bridge can prevent errors later in the model.

When the bridge is created, it can be imported automatically into the model. So the bridge file is exported from SMS, but then SMS imports it automatically. To import the bridge automatically, select the Add 3D Bridge UGrid to SMS on OK option in the Bridge dialog. This eliminates the need to search for it then import it.

However, if the 3D bridge file is moved, it's important to keep in mind that two files were created by modeling the bridge: an XMUGRID file and a PRJ file that contains the projection for the UGrid. These files should be kept together.

Finally, modeling piers is sometimes an important part of modeling a 3D bridge. The top and underside of a 3D bridge are defined using XY Series Editors accessible in the Bridge dialog. When defining any elevation changes in the 3D bridge, the distance (x) values cannot be identical to each other. This means it’s impossible to create a precisely vertical slope using this tool. To approximate a vertical slope, first input distance values that are very close to each other (e.g. 79 and 80). Then, pair them with elevation values that reflect the change in elevation.

Please keep in mind that piers used for an SRH-2D pressure flow model should not be modeled using the 3D bridge tool. Piers in that kind of model should be modeled using voids in the mesh.

Use these tips in creating a 3D bridge in SMS 13.2 today!

Blog tags:

SMS

How to Export Contour Lines as Shapefiles in SMS

By aquaveo on August 10, 2022

Have you been wanting to export the contour lines in your SMS project as a shapefile so they can be opened in a different application? SMS allows exporting contour lines as a shapefile. This post will explain how to export contour lines as shapefiles.

Saving your contours as a shapefile requires your project to be set up correctly. Save the contours as a shapefile by doing the following:

Make sure the contours you want to convert to a shapefile are set to Linear in the Display Options. To do so, open Display Options and click on the page for the geometry that has the contoured dataset loaded (e.g. mesh, UGrid, etc.). First, make sure that contours are turned on. Then, click on the Contours tab. In the Contour Method in the top left, make certain the first dropdown is set to "Linear".
Make sure the desired dataset is active in SMS. This can be done by clicking on the dataset in the Project Explorer.
Once you’ve clicked Save, a dialog opens that gives you options for converting project information to a shapefile. Select one of the contour options. The “Mesh Contours → Arc Shapefile” option is usually best.
Now open your shapefile in the appropriate GIS software. The contour lines will appear as arc lines.

Example of Exporting a Shapefile from SMS

If you encounter issues with the shapefile, start by checking the folder where you saved the file. Make certain that all of the necessary files for the shapefile are there, including a projection file.

Another item to check is that everything you want in the shapefile is displayed correctly in the Graphics Window before you export. Try using the Uncheck All command in the Project Explorer and then checking only the desired geometry. This could allow you to more clearly see the contours as they will appear in the shapefile. You might also consider using the display options to turn off the geometry elements. This would also allow for clearer visualization of the contours. Once you can see the contour lines clearly, use the display options to adjust the contour lines if needed. Finally, there may be some differences between how SMS displays a shapefile and how other GIS applications display the shapefile. Opening the shapefile in SMS can help you determine if this is the case.

Be aware that selecting the Mesh Contours → Polygon Shapefile option when exporting the shapefile causes SMS to create a shapefile with only polygons. This might not accurately reflect the linear contours displayed in SMS since some of them might be only line segments.

Try out exporting contour lines as shapefiles in SMS today!

Blog tags:

SMS