Trouble running unsteady simulation.

[Anonymous]

Hello, I am having some trouble running an unsteady simulation, with my model going unstable immediately. Below are my results. any help would be greatly appreciated.

Geometric Preprocessor Version 4.1.0 Jan 2010
17 Internal Boundary curve(s) have been read in and will not be recalculated

Finished Processing Geometry

Performing Unsteady Flow Simulation Version 4.1.0 Jan 2010

**** Solution Solver Failed ****

Minimum error exceeds allowable tolerance at 31DEC2013 2400

WCW 5 5 399.9997
WARNING!

***** Extrapolated above Cross Section Table at: *****

EW2 1 from R.S. 999.9999 to 799.9999
WCW 9 9 R.S. 599.9998
WCW 11 11 R.S. 277.4888
WCW 11.1 1 from R.S. 107.0433 to 66.43826
WCW 12.1 1.2 R.S. 1800
WCW 12.1 1 R.S. 291.8402
WCW 12.1 1 R.S. 81.0185
WCW 13 13 from R.S. 1892.266 to 1522.128

Finished Unsteady Flow Simulation

Writing Results to DSS
Finished Writing Results to DSS

Reading Data for Post Process
Simulation went unstable at: 01Jan2014 00:00:00
No data for post processing

[Anonymous]

This is my most recent result. Once again, any help would be greatly appreciated.

Geometric Preprocessor Version 4.1.0 Jan 2010
17 Internal Boundary curve(s) have been read in and will not be recalculated

Finished Processing Geometry

Performing Unsteady Flow Simulation Version 4.1.0 Jan 2010

**** Solution Solver Failed ****

Minimum error exceeds allowable tolerance at 31DEC2013 2400

WCW 11 11 4600

Finished Unsteady Flow Simulation

Writing Results to DSS
Finished Writing Results to DSS

Reading Data for Post Process
Simulation went unstable at: 01Jan2014 00:00:00
No data for post processing

[Chris G.]

Try running a steady flow version of this project. Then look for errors (summary of errors warnings notes) and places where the computed water surface elevation defaults to critical depth. Get it all fixed up nice in steady flow, then retry in unsteady. In unsteady, make sure your initial conditions are good and consistent. For example, if your first time step flow is 100, then your initial conditions flow should also be 100. Make sure your computation time step is appropriate (not too big). And make sure you have enough water in your reach (RAS will crash if it goes dry, or even too close to dry). The steady flow version you run should reveal if this is a problem.

[Anonymous]

Try minimizing the calculation time. It will take some time but should work.

[Author]

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