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-   -   Running simulation until certain condition is reached (http://www.cfd-online.com/Forums/cfx/92582-running-simulation-until-certain-condition-reached.html)

elys September 19, 2011 07:20

Running simulation until certain condition is reached
 
Dear all,

I have looked through the tutorials and made some searching on the net, but I couldnt find a solution to my problem: Lets say I have a bottle with just one outlet (static pressure; 1 atm/Bar) and a steady state analysis type. The pressure in the bottle is set to e.g. 10 Bar (e.g. ideal gas or Redlich/Kwong CH4) and I want to know the physical time passing by when the gas exhausts through the bottleneck. Do I have to set a monitor point of some kind? How do I set the solver control, so that the run finish automatically if the interior pressure reaches the static pressure from the BC?

Any hint would be greatly appreciated,

Thanks in advance!

Ben

ghorrocks September 19, 2011 07:38

I do not know the details of what you are modelling but it does not sound like a steady state model. You need to model this transient. Alternately, you may be able to do a series of steady state runs are various pressures (assuming the pressure drop all occurs at the exit) and then use a simple control volume solver to work out the pressure versus time.

elys September 19, 2011 08:03

Thanks for your answer, that sounds reasonable. I try both ways, the extrapolation from various stready state runs and the transient approach.

Thanks again for the quick reply!

Ben

ghorrocks September 19, 2011 19:04

I did not propose an extrapolation from steady state runs. I proposed a psuedo-steady state approach where you assume the transient flow can be represented by a series of steady state conditions.


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