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Author Topic: Pyrosim, Smokeview file not found and HVAC problem  (Read 5308 times)

Torbjørn Haugen Knutson

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Pyrosim, Smokeview file not found and HVAC problem
« on: March 23, 2015, 07:00:00 am »

Hi.

I have two problems, which I hope some of you can help with:

First and foremost: When I try to run the FDS-simulation, it states: ***Error: Smokeview file, ss1.smv, not found

I'm worried that the model is too complex, but in that case, how can I be sure?

The second problem is a peculiar one: I have attached nodes to one (1) duct and specified their coresponding vents. The program even has a help function that states that only one duct can be attached for this function. Trying to run the simulation, it states that the follwing: "internal DUCTNODE" must have at least two attached ducts".

Thanks for your time,
Torbjørn
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Charlie Thornton

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Re: Pyrosim, Smokeview file not found and HVAC problem
« Reply #1 on: March 23, 2015, 10:47:29 am »

The Smokeview error message:

***Error: Smokeview file, ss1.smv, not found

Means that the simulation did not run and never generated an output file. If FDS is producing an error message about the HVAC system (i.e. the internal DUCTNODE error), then the error is preventing FDS from running the simulation.

If you can share your file here or send it to support@thunderheadeng.com, we might be able to help you figure out what is going on with the duct-node-vent connection.
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Torbjørn Haugen Knutson

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Re: Pyrosim, Smokeview file not found and HVAC problem
« Reply #2 on: March 24, 2015, 04:13:39 am »

Thanks for your response.

I had some feedback on another discussion group, where I was told to simplify the model, which I have done. I was also told that the nodes had an air flow into them, but not out. I can see this being a problem, but I couldn't find anywhere to edit this in the nodes.

I hope you can help me.
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swenson

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Re: Pyrosim, Smokeview file not found and HVAC problem
« Reply #3 on: March 24, 2015, 04:59:01 pm »

First, an interesting model, so good work there. However, there were several problems with this model that needed to be fixed, but the errors are understandable.

1. Because the model is complex, I simplified it and deleted most of the geometry. I retained the ceiling.
2. To help understanding, I used Grouping to organize the model.
3. You might want to consider multiple meshes and parallel processing

Here are a list of changes to the model.

1. Deleted an extra Vent.
2. Changed all HVAC ducts to reference the HVAC fan
3. Added the inlet vent and connected the vent to an HVAC node, then made a new HVAC duct that connects the vent to the central distribution node. This is necessary because an end node can only have one duct attached. See the image.
4. Reversed flow direction.
5. Outlet vents were so small they were collapsing to a point (remember that FDS moves all geometry to the mesh coordinates. If the mesh is large, then very small objects collapse to a point.

See the attached images to understand what I did. You will need to go back to your original model and make the same changes.
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Torbjørn Haugen Knutson

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Re: Pyrosim, Smokeview file not found and HVAC problem
« Reply #4 on: March 26, 2015, 07:59:50 am »

Thanks for your help.

Here's a new model, more simple than my initial one. Is it still too complex?

Now I get a different error message: "Cannot specifiy fixed flows for all branches of internal DUCTNODE: Node_HVAC_central" This node is the one between the initial ducts and the duct to the end node. I have triple checked all flows in the model, both total in- and out-flows, as well as the outflow of the more "complex" HVAC system in the ceiling. Whatever I do, I always encounter this error.

Do you have time to help me with this, please?

Kind regards,
Torbjørn
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swenson

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Re: Pyrosim, Smokeview file not found and HVAC problem
« Reply #5 on: March 26, 2015, 09:29:44 am »

Torbjørn,

First, there is no problem with complex models, it is just difficult to debug them.

The simple answer to the problem is that you are not allowed to specify the flow on all ducts connected to an internal node. If you specify the flow, you apply to many boundary conditions to the problem. See the attached image. So, remove the fan from the Duct_HVAC_exit (both 1 and 2). That removes the problem, but now there is another problem that causes FDS to crash without a message.

I can spend some time on Monday looking at this.

What I would do it take your current model and simplify so there is only one duct network. Make sure this works, then start to add the other networks back in. That will isolate the problem.

Best wishes,
Dan
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Torbjørn Haugen Knutson

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Re: Pyrosim, Smokeview file not found and HVAC problem
« Reply #6 on: March 30, 2015, 08:54:26 am »

Thanks a lot for you feedback.

I changed the geometry of the burners to default, which solved the last problem.

Thanks again for all your help.
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