1d/2d modeling Unsteady Flow Analysis error

[Reylin]

I have been trying to run a river model with an applied terrain using Beta 5.0 to only a specific part of a reach. However, the solver has always failed. I tried the instructions regarding the HTab parameters, still it won’t work. This time, I reduced the time step to 30 seconds and these were the results.
(I’ll try to follow up posting the whole file later.)

And by only a specific part of the model, I mean it like this:

Performing Unsteady Flow Simulation HEC-RAS 5.0.0 Beta August 2015

Maximum iterations of 20 RS (or Cell) WSEL ERROR

26SEP2009 02:22:30 Marikina River Upper_marikina_z 23394 22.53 0.020
26SEP2009 05:56:09 Marikina River Upper_marikina_z 22446.8* 28.65 0.027
26SEP2009 06:00:33 Marikina River Upper_marikina_z 22696.9* 35.46 0.040
26SEP2009 06:00:39 Marikina River Upper_marikina_z 21155.0* 27.85 0.020
26SEP2009 06:00:42 Marikina River Upper_marikina_z 22696.9* 36.34 0.201
26SEP2009 06:00:48 Marikina River Upper_marikina_z 22512.1* 43.68 0.032
26SEP2009 06:00:51 Marikina River Upper_marikina_z 22604.5* 36.08 0.993
26SEP2009 06:01:15 Marikina River Upper_marikina_z 22446.8* 41.88 0.213
26SEP2009 06:01:18 Marikina River Upper_marikina_z 22604.5* 38.05 1.767
26SEP2009 06:01:21 Marikina River Upper_marikina_z 21745.* 32.40 0.069
26SEP2009 06:01:33 Marikina River Upper_marikina_z 22512.1* 47.50 0.173
26SEP2009 06:01:36 Marikina River Upper_marikina_z 22604.5* 37.83 1.166
26SEP2009 06:01:45 Marikina River Upper_marikina_z 22604.5* 39.97 1.976
26SEP2009 06:01:51 Marikina River Upper_marikina_z 22512.1* 49.23 0.107
26SEP2009 06:01:54 Marikina River Upper_marikina_z 22446.8* 40.14 1.887
26SEP2009 06:02:03 Marikina River Upper_marikina_z 22604.5* 40.15 1.131
26SEP2009 06:02:06 Marikina River Upper_marikina_z 22789.2* 40.19 0.292
26SEP2009 06:02:12 Marikina River Upper_marikina_z 22446.8* 42.87 3.707
26SEP2009 06:02:15 Marikina River Upper_marikina_z 22120.8* 42.59 0.261
26SEP2009 06:02:21 Marikina River Upper_marikina_z 22512.1* 44.19 5.319
26SEP2009 06:02:30 Marikina River Upper_marikina_z 22466 54.45 5.458
26SEP2009 06:02:33 Marikina River Upper_marikina_z 22512.1* 41.90 0.730
26SEP2009 06:02:39 Marikina River Upper_marikina_z 22466 63.30 5.612
26SEP2009 06:02:42 Marikina River Upper_marikina_z 22512.1* 56.68 4.788
26SEP2009 06:02:48 Marikina River Upper_marikina_z 22512.1* 88.76 6.492
26SEP2009 06:02:51 Marikina River Upper_marikina_z 22446.8* 71.56 8.311
26SEP2009 06:02:57 Marikina River Upper_marikina_z 22466 141.03 18.341
26SEP2009 06:03:00 Marikina River Upper_marikina_z 22512.1* 111.95 13.109
26SEP2009 06:03:06 Marikina River Upper_marikina_z 22198.2* 318.19 73.182
26SEP2009 06:03:09 Marikina River Upper_marikina_z 22198.2* 234.20 61.609
26SEP2009 06:03:12 Marikina River Upper_marikina_z 19973.2* 15.67 0.114
26SEP2009 06:03:15 Marikina River Upper_marikina_z 19524 24.47 12.407
26SEP2009 06:03:18 Marikina River Upper_marikina_z 20977.5* 10799.05 35.242

**** ERROR: Solution Solver Failed ****

Minimum error exceeds allowable tolerance at 26SEP2009 06:03:18

Marikina River Upper_marikina_z 20453.*

***** Warning! Extrapolated above Cross Section Table at: *****
(The extrapolation may have been caused by model instability)

Marikina River Upper_marikina_z from R.S. 27024 to 26901.6*
Marikina River Upper_marikina_z from R.S. 26820 to 20244.8*

***** Warning! Extrapolated above/beyond Rating Curve (Bridge/Culvert/etc.) *****
(The extrapolation may have been caused by model instability)

At River Marikina River Reach Upper_marikina_z R.S. 27619
At River Marikina River Reach Upper_marikina_z R.S. 19373

*Note that I also tried adding cross sections. However, after interpolating them, I have to remove almost everything of them since they won’t match the said terrain.

Any help would be appreciated. I badly needed this for my project. Thank you, guys.

[Anonymous]

Have you finish this problem? I have the similiar problem, and i have changed the Htab parameter until the computation line is close to WSE, but the error still appear. What should i do? Is this caused by the boundary condition or geometry??

[tesfay haile tesfay]

hi dears i have the same error with all of you? have you ever solution regarding this problem? please share me.

[Anonymous]

This is just a common unsteady model error. Either the model is drying out somewhere or the time step is not appropriate. Decrease your time step to something like 1 second and try it out. If not add minimal flow to cross sections with errors in initial conditions

[Author]

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