Bed Load Sortie File does not match Blue Kenue results

System Modules GAIA / SISYPHE
1

Dear [name removed],

I’m currently experimenting with a bed-load time series in GAIA (v8p4) and trying to match the boundary mass balance from the listing file (attached) with what I get when I post-process the SELAFIN results in BlueKenue.

When looking only at the listing File, the bed load time series is implemented correctly and for example ca. 28 kg/s after 10:30 hr enter the domain over all.

But when looking at the BlueKenue results of the magnitude of the variable SOLID DISCH XY(see attached picture) at this time step it doesn’t match. Of course the unit is different, but I solved this issue by integrating over the distance between the nodes, which is ca. 5m.

I created a time series over the simulation time of 13 hrs which can find attached as well. It has to be said that the bed load of 20 kg/s is probably too high for this flow and it accumulated very close to the inflow boundary. It’s quite possible I’m missing something important here.

What do you think? Is the listing value the imposed value and not the actual transport?

I uploaded all files mentioned here: https://www.transfernow.net/dl/20260604exKJCoat

Thanks for your insights!

2

[name removed],

so far as I know the solid discharge in the results file are the values which can be transported theoretically in case there is no sediment deficit. In case of multi grain or rigid bed there might be not enough sediment available in the subroutine. In case of finite element the fluxes (FLODEL) will be reduced in the positive_depth subroutine to the available sediment budget. This is not calculated back to the QS value.

For monitoring inside the model area you can use the fluxlines. They take the reduced fluxes into account.

Hope this helps

[name removed]

3

Hi,

I’m not sure if this could also explain the difference, but in the past I struggled with this: taking into account the porosity or not in calculating the solid discharge.

[name removed]

4

Hi:)

Thanks for the suggestion!

Yes, I was thinking about that too, but i tried different densities and it did not work out.

5

Hello [name removed],

that is probably the case. I have multiple grain size classes. I tested the model with only one grain size and depending on the size the influx varied.

I tried to implement the fluxlines, but i was not successful in getting a listing or another output for GAIA. I’m running it in parallel (12 cores) with v8p4. But i also ran it with one core as well and it didn’t make a difference.

I tried to implement the fluxlines into GAIA by adding the keywords to the GAIA steering file:

FLUXLINE = YES

FLUXLINE INPUT FILE = fluxline.txt

I added them to the hydraulic steering file as well and for that i got an output in the listing.

The fluxline.txt file looks like this:

2

2607.0 108.0 2750.0 106.0 0.0 0.0 3160.0 19700 1

1328.0 19649.0 1480.0 19619.0 0.0 0.0 3160.0 19700 1

Do you have suggestions, why it is not working?

Thank you!