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> Singularity Problem
PredKirK
post Oct 15 2012, 05:48 PM
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ah thank you now it works fine


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Dymola 7.1 , trying OpenModelica -> Hardware in the Loop, Real Time simulation
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ETH
post Oct 14 2012, 07:54 PM
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Hello,

Closed Volume and Boundary elements have been built to be compliant with Finite Volume method.
It is sometimes possible to connect volumes but it is really not recommended in the general case because states should evolve exactly in the same way.
And it is not really physical. There are often relations which gives mass flow between volumes and volume states.
In your case, you should then put flow models between volumes. The element you have made to connect volume is only a connection which equal states of the connected volumes.
Try to put elements with flow models like pipes between volumes and everything should assure you to be able to simulate.

Best regards,




QUOTE(PredKirK @ Oct 11 2012, 05:41 PM) *

Hi there,

I hope that someone can help me this time.
I reduced my Error messages during translation progress to the main cause.

When I try to combine two or more volume(vessels), I get the singularity-message.
I want to combine 2-to-n volumes, which should be served by a mass_flow which splits um in n streams.
Every stream goes through a volume-vessel and afterwoods all streams are combined again and leave my model reunited^^.

I think that I need some information, that when I connect all Ports after passing the volume, that there is no backflow attempt. So that Dymola knows that there is just one way for the fluid to flow (port_a to port_b)

I created something like a stopbackflow_valve, but it doesn't work or is this the wrong idea?

In the attachment is a small example and my failed way of solving it.... everything is in it.

Thank you for your help and experience

PredKirK

+++++++++++++++++
++ Dymola 7.1+++++++
++++++++++++++++++

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PredKirK
post Oct 11 2012, 05:41 PM
Post #3


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Group: Members
Posts: 5
Joined: 18-September 12
Member No.: 625,864



Hi there,

I hope that someone can help me this time.
I reduced my Error messages during translation progress to the main cause.

When I try to combine two or more volume(vessels), I get the singularity-message.
I want to combine 2-to-n volumes, which should be served by a mass_flow which splits um in n streams.
Every stream goes through a volume-vessel and afterwoods all streams are combined again and leave my model reunited^^.

I think that I need some information, that when I connect all Ports after passing the volume, that there is no backflow attempt. So that Dymola knows that there is just one way for the fluid to flow (port_a to port_b)

I created something like a stopbackflow_valve, but it doesn't work or is this the wrong idea?

In the attachment is a small example and my failed way of solving it.... everything is in it.

Thank you for your help and experience

PredKirK

+++++++++++++++++
++ Dymola 7.1+++++++
++++++++++++++++++


Attached File(s)
Attached File  SingularityProblem.mo ( 15.29k ) Number of downloads: 478


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