thank you again for your detailed explanation. This is very helpful.

Regarding the `minimum_water_depth`: in my current test model, I use 0.049 m because I start the simulation with an initial water depth of 5 mm in every cell. I had actually chosen 0.001 m initially, but with this value the program eventually stopped responding and got stuck, so for the current test I changed it to 0.049 m.

Regarding your hint about `geofile_Grid.err`: I cannot find this file in the Explorer directory of my simulation. It does not seem to be generated. Is there something I need to enable in order for this file to be written?

I have also tested `different CFL numbers´ in the meantime: 1.0, 0.95, 0.5 and 0.1. As expected, the number of mass conservation warnings decreases with decreasing CFL, as does the accumulated volume reported in these warnings. At the same time, the computational time increases, as does the total volume in the system. This seems plausible to me, since the numerical mass error is smaller with a lower CFL number.

I also tried to establish a `mass/volume balance´. I used two different approaches:

     1. I integrated the discharge time series using the trapezoidal rule. I integrated the rainfall input to obtain Q_in and the discharge at the downstream boundary to obtain Q_out. Based on this, I expected the remaining volume (water stored in the domain) to be:

          water stored in the domain = Q_in - Q_out - mass error.

     2. I also looked at the `balance.dat` file, which contains a volume value at the end of the simulation.

From my understanding, the volume at the final time in `balance.dat` should correspond to the remaining volume at the end of the simulation obtained from the first approach. However, the two values do not match for any of the CFL numbers I tested.

Interestingly, the difference between the two approaches becomes larger as the CFL number decreases.

Could you perhaps help me understand how the volume given in `balance.dat` is defined and how it relates to the integrated inflow/outflow and the mass conservation error? In particular, I would be very interested to know whether these two approaches should indeed result in the same volume.

Thank you very much again for your help and for taking the time to look into this.

Best regards,
Elli

I´would like to restart one of my BASEMD modells that is made in BASEMENT 4.1. My initial parameters are

initial I set "file" = results.h5       
"HYDRAULICS": {
          "INITIAL": {
            "type": "continue",
            "file": ".../result.h5"
            "restart_solution_time": -1
          },

Running this creates the following error:

WARNING -> Determining the existing solution times failed: Accessing the HDF5 group
   '/RESULTS/CellsAll/Depth' failed.

WARNING -> Parse error when trying to read the HDF5 restart file: Accessing the HDF5
   group 'RESULTS/CellsAll/Depth' failed..

#=========================
If i change to:

"HYDRAULICS": {
          "INITIAL": {
            "type": "continue",
            "file": ".../restart.h5"
            "restart_solution_time": -1
          },

I get this error:
WARNING -> Not all needed data could be found in restart file.

ERROR -> ERROR opening HDF5 file './\LHSG_restart.h5', error: Opening the HDF5
   file at './\LHSG_restart.h5' failed.
When I look at the result.h5 in hdf5 viewer it seems empty but I do get

#========================

When I look at the results.h5 file inside HDFviewer. di dictionary structure is like this:
results.h5
  .config
  Domain
    LHSG
      .config
      CellsAll
      NodesAll
      RESULTS
        CellsAll
          Depth
             0   - includes data from timestep 0.0 (no data)
             1   - includes data from timestep 4500.000....
          VelocityX
             0   - includes data from timestep 0.0 (no data)
             1   - includes data from timestep 4500.000....   
          VelocityY
             0   - includes data from timestep 0.0 (no data)
             1   - includes data from timestep 4500.000....

The restart file contains the this data as well.

Any ideas or suggestions on what I should try to do to get it running??

Best Regards// Mattias

Is there a rule-of-thumb regarding the mesh refinement (element size, relationship Q to required nodes/width of stringdef) for inflow- and outflow boundaries?

There is not really a rule for this. But if I had to suggest something, I would say at least 5 to 10 cells over the width of your inflow/outflow boundary. Of course this depends, among other things, on the width and lateral variation of your inflow/outflow cross section.

I also understand your frustration with this bug. Unfortunately, we did not have the capacity to fix this until now.

@Stefano: From the paths in the XDMF it seems that this was a BASEMD simulation? Unfortunately, for BASEMD the HDF5 output is not working yet and therefore, also the XDMF import into QGIS or ParaView does not work. But you can generate other outputs for BASEMD that are compatible with QGIS (sms or shape (=shapefiles)) or ParaView (vtk).

Best regards,
Matthias

Ps: Please choose a meaningful title for topics in the future

That's an interesting topic and discussion. For the linked hq-relation BC it would be great if the user could choose the BC type at the linked inflow (from the mesh perspective), e.g. uniform_in or froude_in.

Br, Lukas

This is quite an old topic, but I am stuck with the same issue and there doesn't seem a solution proposed here. I have the issue on an inner boundary weir in 2D model. Anyone who knows what this error means? In my case I only have it when my discharge becomes very high. Is there a problem with the water flowing on the side of the weir? It could be the mesh is not good enough around the weir, since it is based on measured cross sections. I already tried to add some elevation points manually (on the banks parallel to the weir), and I managed to model up to a higher discharge, but not yet to the maximum discharge I need. But I am not sure if this is the way to fix it.
Any advice is welcome.

Thanks

1. use the IOUp boundary condition instead of the transport_capacity;
2. build a fake channel with constant slope and regular geometry upstream of your domain with gravitational transport on all elements;
3. try to play with the slope at the inflow boundary

Best
Matteo

have you run some "extreme" tests, like e.g. extracting all the water with the sink?

Matteo

cheers
Alyssa

recently I have solved many problems due to your help,thank you.
And now I'm working on a case about event-driven-simulation,Is BASEMENT suitable for this? first I set the
initial condition for no discharge and simulate the attenuation of waves,and then in one specific time Iwant to input another water level for event-driven-simulation. Therefore which bolck should I choose?
thank you!

so:

1. ok, then it is indeed an hdraulics problem. It is probably related to your mesh, but without seeing the mesh and the .bmc file it is hard to tell;
2. you should define holes in your mesh yourself, otherwise it is unlikely that you have them, refer to the tutorials to understand how to make holes in your mesh;
3. actually if you have mass balance problems it is not a good sign: do you results make sense?
4. With attenuation of waves you mean the effect of waves runup with diminishing water depth? There are specific numerical models for that, I am not sure if basement is suited for that. What you could do is to use a fixed water level downstream boundary condition to simulate the effect of a large water body at the downstream end of your watercourse.

I hope this helps,
cheers

the meaning is that you have to write a table with time on the left and water surface elevation on the right, like
0, 100
1, 100.1
2, 100.15

and so on.

A negative water surface level might be possible if your boundary is below the sea level, is this your situation?

I'm simulating a case about Monai Tsunami.I  successfully generated mesh by BASEmesh.There is a file for inflow boundary-——time and correspongding water level. which type should I choose as boundary condition? Zhydrograph?any other notes? I failed for several times.and i can not find a solution in forum.How can I ? expecting your reply!
thank you