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Chiara

No Flow through RMA2 Model

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Hi all,

I am running an RMA2 model (steady state to begin with) and although the model runs, I am not getting any flows. The results do not include flows, there are no velocities in the velocity output, and in the .ot2 file, all flows on the boundaries are zero. Also in the .ot2 file, the boundary conditions seem to be read in, but for some reason aren't applied. :(

Why is this?

Also, how does the spindown function work? I have tried using it, but it gets 'terminated' each time. The online help describes how it works, but not how to use it!

Some info on the model:

-Upstream boundaries are constant

-Downstream boundaries are rating curves (I have tried constant heads here as well)

-An initial water level for coldstart has been applied (at an elevation jsut above the highest elevation in the mesh).

Thanks

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I just saw your other post detailing a similar problem. I guess pointing you to the online help isn't going to help you.

The spindown functionality automates what is called an incremental loading strategy. The first step to incremental loading is getting a model to run with simplified boundary conditions. Generally, this means lower flowrates, higher downstream water surface elevations, or both. Once you get an initial solution, you feed the results into a new simulation with boundary conditions that are closer to the ones you want in your final model. This process is repeated until you can run the model with the final boundary conditions.

To use the steering module, you set the boundary conditions to what you want them to be in your final runs and choose Data | Steering Module. In the RMA2 Spindown section there are toggles to turn on different options that you want SMS to adjust in order to spin down the model. I always try to spin only on water surface elevation initially. If this doesn't work, I add flow. If both of these won't work, I try to identify if there is anything in my model that is making convergence difficult. Look for convergence parameters in the ot2 file and see if there is poorly misrepresented geometry in the area of the node with the maximum change between iterations. I generally don't specify initial conditions.

If you are trying to use the steering module and it terminates unsuccessfully, I'm guessing that it is having trouble getting the initial run working. You can verify this by looking at the steering_status.txt file in the directory you are running in. I would try to get a manual run working even if it means making a much higher water surface elevation or lower flowrates. Once you get a manual run working, I would use the steering module but specify the hotstart file from your manual run. This will use your manual run as a starting point and incrementally load the model trying to get to your final boundary conditions.

Could you contact technical support and get them your files support@aquaveo.com? I can't see anything in your description that would lead the model to not run correctly. You may want to check your settings for eddy viscosity and compare them with the RMA2 manual for the units that you are using to make sure they are appropriate.

Hi all,

I am running an RMA2 model (steady state to begin with) and although the model runs, I am not getting any flows. The results do not include flows, there are no velocities in the velocity output, and in the .ot2 file, all flows on the boundaries are zero. Also in the .ot2 file, the boundary conditions seem to be read in, but for some reason aren't applied. :(

Why is this?

Also, how does the spindown function work? I have tried using it, but it gets 'terminated' each time. The online help describes how it works, but not how to use it!

Some info on the model:

-Upstream boundaries are constant

-Downstream boundaries are rating curves (I have tried constant heads here as well)

-An initial water level for coldstart has been applied (at an elevation jsut above the highest elevation in the mesh).

Thanks

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Thanks Rusty,

I have previously tried running the model with both traditional eddy viscosities and Smagorinsky. I have checked the manual and my units/numbers are correct and reasonable. I am still having the same problem- the model is running but there are no flows. I have run the model with and without initial conditions, and I still get the same response from the Spindown- termination. When I check the SteeringStatus.txt, it says the Steering Process was successful. (?) When I use the Steering Module, water surface elevation toggle, do I need to specify initial conditions? (The option is a percentage- I am assuming a percentage of the current water surface elevation?)

I have even recreated the mesh to simplify it in case this was the problem, and apparantly this was not the case.

I will contact the support team to see if they can help.

Thanks

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