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How to create permeable surface on inlet boundary? |
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April 6, 2009, 09:33 |
How to create permeable surface on inlet boundary?
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#1 |
New Member
Michael
Join Date: Apr 2009
Posts: 20
Rep Power: 17 |
Hi all
I have to model a permeable surface upon an inlet boundary. From the surface I also need to specify a heat flux. The problem I have tried to illustrate on the figure at the link: The way I have tried to handle it is to define the geometry of the room and define the inlet and outlet by the “Imprint Faces” command. Then I define the surface as a solid which I use the “Frozen” command and then I put the room into an enclosure so I have one part consisting of two bodies. But when I go to the pre in CFX I can not find out how to define it as a permeable surface without a thickness. How can this be done? Kind regards Michael |
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April 8, 2009, 04:25 |
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#2 |
New Member
Michael
Join Date: Apr 2009
Posts: 20
Rep Power: 17 |
Not ideas how to solve the problem?
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April 8, 2009, 09:19 |
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#3 |
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 449
Rep Power: 20 |
hi,
did you get a "surface" in Pre on which you could apply a bc and your question is how to do that (create the bc for a permeable surface)? OR you didn't get a surface and you know how to setup a permeable surface? neewbie |
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April 8, 2009, 16:17 |
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#4 |
New Member
Michael
Join Date: Apr 2009
Posts: 20
Rep Power: 17 |
Hi Neewbie
I have the surfaces of the volume in Pre where I can apply bc but I have to define the heat flux by a subdomain with a heat load from the volume given in W/m^3 and I would like a surface without a thickness if possible. I think this is caused by the way I have define the geometry of the room. First I have generated the room geometry and then use the imprint command where the inlet and outlet is located. Then I generate a solid volume with a small height which i define as frozen. Then I put the room to an enclosure and jump to CFX-mesh where I generate a grid. So to sum up maybe I have problem both to generate the geometry correct and to get the surface into Pre. If possible I would like not to model the surface as a porus domain since this increase the computing time. Kind regards Michael |
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April 9, 2009, 07:37 |
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#5 |
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 449
Rep Power: 20 |
hi,
so did you get a volume for the "quasi-surface"? I´m asking because with the imprint you won´t get a volume. Try to sepparate the volumes by creating a multibody part in the DM (unfortunatly i don´t know the correct english option ) and make the "surface" one element over hight, mesh them separatly and connect them by ggi or 1to1. neewbie ps:When defining bc names in cfx-mesh all earlier component names (from DM) will be overwritten. |
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April 10, 2009, 12:36 |
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#6 | |
New Member
Michael
Join Date: Apr 2009
Posts: 20
Rep Power: 17 |
Hi neewbie
No I don't get a volume when I use the imprint faces command since this give me a 2D surface as you also talk about. I think you are talking about to form one part from multiple bodies in DM? This I have done where I define the “surface” as a frozen solid volume which gives me the opportunity to make one mesh and don’t have to define permeable subdomain. But if I make to models and to mesh which I “melt” together will it then be possible to define on of the side of the volume as a permeable surface? kind regards Michael Quote:
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April 12, 2009, 18:38 |
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#7 |
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 449
Rep Power: 20 |
hi,
i would guess you have to modell the "surface" as a volume momentum source. So it would be a sepparate volume mesh. Or how do you do it? neewbie |
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April 13, 2009, 10:49 |
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#8 | |
New Member
Michael
Join Date: Apr 2009
Posts: 20
Rep Power: 17 |
Quote:
I have made a solid frozen volume which are enclosured bu a large room. The mesh is then also generated through the volume and then I can define a volume source in CFX-Pre. So to model it as an surface I have made the height "small". Is this the way to handle it? Kind regards Michael |
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April 14, 2009, 13:51 |
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#9 |
New Member
Michael
Join Date: Apr 2009
Posts: 20
Rep Power: 17 |
Hi all
I have an extra question to my problem. The area where the inlet is model I have defined as a surface by the imprint command. In CFX-Pre I saw that it is possible to define a heat source on the “inlet surface”. The problem is then that the surface representing persons is around 10 m2 located in the middle of the inlet surface which has a total area 65.9 m2. So I was wondering if a way could be to define a surface surrounding the small surface as one part of the inlet and the enclosed surface as another part of the inlet which also release a heat source? The next problem is then how to define the total incoming mass flow rate correct. If I know the total mass flow rate are 2.04 kg/s would it then give the “correct” flow if I divided the mass flow rate into two quantities of 1.728 kg/s and 0.312 kg/s for the two areas on 55.9 m2 and 10 m2 respectively? Kind regards Michael |
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April 15, 2009, 04:35 |
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#10 |
Senior Member
Matthias Voß
Join Date: Mar 2009
Location: Berlin, Germany
Posts: 449
Rep Power: 20 |
hi,
by using the imprint command twice you should be able to get such a geometry/faces- and by applying the partial massflows you will end up with your desired totalmassflow. neewbie |
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April 15, 2009, 06:10 |
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#11 | |
New Member
Michael
Join Date: Apr 2009
Posts: 20
Rep Power: 17 |
Quote:
Thank you for your reply. It seems that my idea was in the right way then Kind regards Michael |
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