User Forum of Software BASEMENT

Yang He

User

Registered: 2024-06-02

Posts: 8

Error related with gate as inner boundary

Hi!

I'm trying to simulate a single river with a gate in it. The river is 56km long with 404 cross sections. Now I only do the hydraulic simulation.

Based on the “Test case Inner Gate” (https://forum.basement.ethz.ch/viewtopic.php?id=478), I changed the INITIAL to “backwater” and ran the model. However, it shows the warning and error information as below:
“
WARNING -> Backwater calculation reached a supercritical
   cross section (cs_4):flow is set to critical flow.

ERROR -> Newton-iteration to calculate water surface elevation (z) as a function
   of the wetted area (A) failed for cross section 'cs_202'. Maximal number of
   iteration (1000) was reached.
   Requested A = 8.59862e+26
   Current z   = 0
   A-Anew      = 1000
   [z0,z1]     = [1293.12, 1322.46]
   [A0,A1]     = [0, 2022.85]
   Please try to (1) start simulation with wetted initial condition, (2) check
   tags in HYDRAULICS -> PARAMETERS -> SECTION_COMPUTATION.
”

According to https://forum.basement.ethz.ch/viewtopic.php?id=5503, I changed the slope of downstream boundary condition. But it does not work.

According to https://forum.basement.ethz.ch/viewtopic.php?id=555, I tried “zero-gradient” instead of ‘hqrelation’ as downstream boundary conditions and changed the “max_interval” and “min_interval”. But they do not work too.

Is there any suggestions that I can have a try?

Thanks for your help.

Best regards,
Yang

Last edited by Yang He (2024-06-18 13:44:24)

Lukas Vonwiller

Developer

Registered: 2014-09-04

Posts: 130

Re: Error related with gate as inner boundary

Hi Yang

Maybe you could try another initial condition, e.g. setup an initial run with dry river reach or with some water depth (e.g. 1 m) along the river reach with a certain discharge. Then use this result as initial condition. Backwater as initial condition (and super-critical conditions within your river reach) with an inner boundary might be problematic also from a hydraulic standpoint and probably difficult to implement in the model.

I hope this helps!

Br, Lukas

Yang He

User

Registered: 2024-06-02

Posts: 8

Re: Error related with gate as inner boundary

Dear Lukas,

Thanks for your suggestion.

I set up a dry river reach without gate, and input 100m^3/s constant discharge until it reach a steady state. Then, I used the resulting data as the initial condition for the model with the gate, using the “continue” condition. Unfortunately, I encountered a similar error as before:

ERROR -> Newton-iteration to calculate water surface elevation (z) as a function
   of the wetted area (A) failed for cross section 'cs_278'. Maximal number of
   iteration (1000) was reached.
   Requested A = 4.42385e+19
   Current z   = 0
   A-Anew      = 1000
   [z0,z1]     = [1145.7, 1161.24]
   [A0,A1]     = [0, 998.863]
   Please try to (1) start simulation with wetted initial condition, (2) check
   tags in HYDRAULICS -> PARAMETERS -> SECTION_COMPUTATION.

For reference, here is the code for setting the gate and SECTION COMPUTATION:

"INNER_BOUNDARY": [
              {
                "type": "gate",
                "gate_type": "sluice_gate",
                "ehead_reference_location": "cs_278",
                "cross_section_name_1": "cs_286",
                "cross_section_name_2": "cs_287",
                "contraction_factor": 0.62,
                "gate_bottom_level": 1136.0,
                "gate_level": 1137.0
              }

"PARAMETER": {
              "SECTION_COMPUTATION": {
                "internal_levees": "on",
                "type": "table",
                "max_interval": 0.01,
                "min_interval": 0.001
              },
              "minimum_water_depth": 0.01,
              "riemann_solver": "roe",
              "simulation_scheme": "explicit",
              "stretch_boundary_elem": "yes"
            },

Is there any other possible solution?

Best regards,
Yang

Lukas Vonwiller

Developer

Registered: 2014-09-04

Posts: 130

Re: Error related with gate as inner boundary

Hi Yang

What happens if you open up the gate a bit more, lets say e.g. gate_level = 1140.0? Without gate everything works?

Br, Lukas

Yang He

User

Registered: 2024-06-02

Posts: 8

Re: Error related with gate as inner boundary

Hi Lukas,

Thanks for the suggestion. After I open up the gate, the model is running successfully now.

Best regards,
Yang