10. Limiting Froude Spatial

10. Limiting Froude Spatial#

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The Spatial Limiting Froude layer is used to set a limiting Froude number for individual FLO-2D grid elements. For example, overland flow on a gentle slope will is likely subcritical so a limiting Froude value of 0.9 or 0.99 can be assigned. If the limiting Froude is exceeded, due to local slope and roughness assignments, the grid element n-value is incrementally increased and maintains numerical stability that might occur for severe supercritical flow.

The limiting Froude is a way to calibrate n-values for the overland grid.

Note

For further discussion on the limiting Froude numbers refer to the FLO-2D Data Input Manual and the FLO-2D Reference Manual.

Digitize or Copy Data#

  1. Select the Froude Areas layer and click Toggle Editing.

  2. Create or copy the polygons that represent the Froude areas to the layer and save them.

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Sample Data#

  1. Click the Sampling Limiting Froude Numbers.

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  1. Once the process is complete OK to close it.

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Troubleshooting#

  1. Create the limiting Froude polygons if they are missing from the Froude Areas layer.

  2. If the Grid layer is empty, create a grid system and try again.

  3. If a Python appears during the sampling process, the attribute table may be missing. Save and reload the project into QGIS and try again.

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