1D culvert model question

[keith marcoe 0]

I am trying to model a culvert passing underneath a road/levee, and am wondering how the mesh cell elevations should be defined in relation to the culvert inverts at this location.  Currently, my mesh elevations are representative of the road surface (approx 5.6 m) elevation, and my culvert inverts are specified in the culvert definition file at lower elevations (3.45 and 3.35 m for US and DS inverts, respectively).  This generates the following warning when the model simulation initializes:  'Culvert upstream invert is less than ground elevation'.

The simulation runs ok, but I would like to know if this is being represented correctly, or if the mesh elevations should be set at, or lower than, the culvert invert elevations.

Attached figure should help clarify.

Thanks

 

DL_culvert_model.pdf

[Toby Devlin 21]

Hi Keith,

You are correct that the elevations of the model may need to be changed. The extreme case is when the cells adjacent to the culvert are so high as to not get wet at all, then there can be no flow through the structure. Even if they are wet however, the flow will be limited as the culvert appears cut off by the bathymetry.

Have you specified the mesh elevations within the .2dm file or through a separate cell-centered csv?

If you have specified through the .2dm, keep in mind that as TUFLOWFV is cell-centered, the true elevation internal to the model will be interpolated from the mesh vertices to the centroid of each cell. This can make things difficult in situations such as yours when attempting to control that cell without changing others.

If not, then it should be a simple method to adjust the elevation of the relevant cells to be equal to or less than the culvert invert, and not affect any other cells.

 

[keith marcoe 0]

Thanks, Toby.

I will create a cell elevation file, and adjust the relevant cells so that they are lower than the culvert inverts.

Keith

[Toby Devlin 21]

Hi Keith,

There are also alternative update options for cell-centered bathymetry such as polylines and polygons. These are all specified in the TUFLOWFV manual section 4.2.2

Toby