Changing geometry in OF: how can I manage this?

samiam1000 · May 9, 2012, 03:22

Dear Foamers,

I have this situation: I have a big domain with 2 fluid regions (air), separated from 2 solid regions. These 2 regions have a 2 different temperatures

I have a steady solution at the time 0-. At the time 0 I suddenly remove the solid region 1 (see the pdf attached), hence the solid region 1 should become a fluid region.

How can I manage such a problem with OF?

Thanks a lot,

Samuele

nimasam · May 9, 2012, 04:26

in other word you have two air region with different temperature that soild is membrane so after time zero it is not important

, so you just need, for initial condition define a non-uniform temperature ( which can be done for your simple geometry with "setField" )

setFieldDict can be found in interFoam tutorial

samiam1000 · May 9, 2012, 05:13

Dear nimasam,

thanks for answering. I think that the point is more challenging: it's like if I have 2 simulations.
The 1st one will allow me to find the 1st steady solution with the door. Then I remove the door.
The 2nd simulation is the non-steady simulation of the transient, once the door is opened. So I need to use the solution of the 1st simulation as the 0-condition for the 2nd simulation.

The challenging point is that I have a region which is a solid in the 1st simulation and fluid in the second one! What I can not und. is how to simulate this and - above all - how to properly set the fluid-fluid interface.

Thanks again.

Samuele

mturcios777 · May 9, 2012, 12:48

When you talk about the regions solid1 and solid2, do you need them to be extended regions? If they are just walls that separate the regions and don't need to be any particular thickness, then you might be able to use the attachDetach boundary condition. I've done a little experimenting with it in 2.1.x, and it works for incompressible flow, both laminar and turbulent (turbulent requires some modifications to your turbulence and transport models as explained here).

Still haven't gotten it working with compressible flow, if you feel this is useful we could put our heads together...

samiam1000 · May 10, 2012, 03:05

Dear mturcios777,

thanks for answering.

Actually, the answer is `yes', I need 2 thick solid regions. The roof remain a solid, also in simulation 2, while the door suddenly becomes a fluid region.

I think we can share our experience to get something good both for us and for the OF community.

What do you think?

Please, send me an email @ samuele.zampini@gmail.com

Thanks a lot,

regards,

Samuele

May 9, 2012, 12:48	It depends...	#4
mturcios777 Senior Member Marco A. Turcios Join Date: Mar 2009 Location: Vancouver, BC, Canada Posts: 740 Rep Power: 28	When you talk about the regions solid1 and solid2, do you need them to be extended regions? If they are just walls that separate the regions and don't need to be any particular thickness, then you might be able to use the attachDetach boundary condition. I've done a little experimenting with it in 2.1.x, and it works for incompressible flow, both laminar and turbulent (turbulent requires some modifications to your turbulence and transport models as explained here). Still haven't gotten it working with compressible flow, if you feel this is useful we could put our heads together...

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May 9, 2012, 04:26		#2
nimasam Senior Member Nima Samkhaniani Join Date: Sep 2009 Location: Tehran, Iran Posts: 1,266 Blog Entries: 1 Rep Power: 24	in other word you have two air region with different temperature that soild is membrane so after time zero it is not important , so you just need, for initial condition define a non-uniform temperature ( which can be done for your simple geometry with "setField" ) setFieldDict can be found in interFoam tutorial

May 9, 2012, 05:13		#3
samiam1000 Senior Member Samuele Z Join Date: Oct 2009 Location: Mozzate - Co - Italy Posts: 520 Rep Power: 18	Dear nimasam, thanks for answering. I think that the point is more challenging: it's like if I have 2 simulations. The 1st one will allow me to find the 1st steady solution with the door. Then I remove the door. The 2nd simulation is the non-steady simulation of the transient, once the door is opened. So I need to use the solution of the 1st simulation as the 0-condition for the 2nd simulation. The challenging point is that I have a region which is a solid in the 1st simulation and fluid in the second one! What I can not und. is how to simulate this and - above all - how to properly set the fluid-fluid interface. Thanks again. Samuele

May 10, 2012, 03:05		#5
samiam1000 Senior Member Samuele Z Join Date: Oct 2009 Location: Mozzate - Co - Italy Posts: 520 Rep Power: 18	Dear mturcios777, thanks for answering. Actually, the answer is `yes', I need 2 thick solid regions. The roof remain a solid, also in simulation 2, while the door suddenly becomes a fluid region. I think we can share our experience to get something good both for us and for the OF community. What do you think? Please, send me an email @ samuele.zampini@gmail.com Thanks a lot, regards, Samuele