unsteady flow encountered error, RasDSSWriter64.ext Exit code = 1

[Joe S.]

Running HECRAS 5.0.1. my 1D is connected to 2D area. how do I solve this error?

Plan: ‘PMF_NF’ (PINELAKE.p04)
Simulation started at: 16May2016 06:00:53 PM
Using 64 Bit Computation Engines

Writing Geometry
2D: Mesh property tables are current.
Completed Writing Geometry

Geometric Preprocessor HEC-RAS 5.0.1 April 2016

Finished Processing Geometry

Writing Event Conditions
Event Conditions Complete

Performing Unsteady Flow Simulation HEC-RAS 5.0.1 April 2016

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

Minimum error exceeds allowable tolerance at 15MAY2016 24:00:00

River #1 Reach #1 50276.83

ERROR trying to write to DSS file
Subroutine DSS_WRITE_HYDRO_TO_FILE
+ IC T = -0.1600

Unsteady flow encountered an error.

Writing Results to DSS

Error with program: RasDSSWriter64.exe Exit Code = 1

Computations Summary

Computation Task Time(hh:mm:ss)
Completing Geometry <1
Preprocessing Geometry(64) <1
Unsteady Flow Computations(64) <1
Writing to DSS(64) <1
Complete Process 1

[cameron]

how is the 1D connected to the 2D area? You may need to lower your time step.

[Anonymous]

i connected 1D to 2D, by dragging the downstream 1D point within the adjacent 2D cell. then connected.

where would I change time step?
Comp interval=12 sec, mapping output interval=6 min.

[cameron]

You need to make sure that there is water in the 2D area at the beginning of the run or else the 1D area will go dry. There are multiple ways of doing this, initial condition of the 2D area or hotstart.

[Joe S.]

I was able to have the model run with a lateral structure (spillway) through the dam. The geometry no longer shows the lateral connected to the cross section below the dam. odd. but it clearly shows there is a connection. I got the model running only the PMF, without dam failure.

For the PMF with dam failure, i am using a renamed geometry temporarily since I have been attempting numourous minor changes. But still does not run to completion. From the visual graphics shown in RAS Mapper, the water literally stops at the 2D interface (adjacent to the 1D). I have the 2D overlapping correctly.
-using full momentum wave for dam failure and better stability.
– tried raising the the 2D initial elevation from 1 to 20 ft vertically.
– tried a smaller 50 ft mesh.
– the end of RS (1D) stream elevation is set at 1325.8. The 2D terrain adjacent elevation is 1325.2. I understand that the 1D channel should be slightly above the 2D.

You mentioned making sure the 2D area does not go dry.
– set the initial 2D elevation at 1330, and even tried higher starting point.
– tried 1 to 3 hours for 2D initial conditions.
– tried 2D initial ramp up fraction 0.1 to 0.6
– tried 1D/2D ramp up from 0 to 20.

the terrain drops gradually from elevation 1330 ft (at the dam) to elevation 1240 ft. so not certain with a 90 ft change, if I should break the downstream terrain into more than one 2D area?? then interconnnect them with SA/2D Area connections.

appreciate any further suggestions and comments.

[cameron]

if you put the files somewhere I can get them, I will take a look.

[Author]

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