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engahmed May 24, 2010 18:40

Interface boundary condition
I am confused about the interface boundary condition??
I have a fluid and a porous medium zones in my problem and I was wondering if I would define the "interface" between them as an interface or as an interior in Fluent so i would be able to study heat transfer between the two zones??

-mAx- May 25, 2010 01:27

Interfaces, in the sense of Fluent, are matching surfaces with different mesh topology.
For instance in 2d, 2 matching interfaces could be one edge with 4 nodes, and the other edge with 8 nodes.
So no relationship with porous iterface in your case. I assume you only need to define your porous volume as separated fluid domain, and then treat it as porous zone in fluent.

engahmed May 25, 2010 10:57

Thank you max. I now know I don't need to define any interfaces in my domain.....May I please ask you another question? I know how to define a porous medium and everything, what is confusing me is the "line" separating the fluid and the porous medium, how to define it? imagine, it is a 2D case with water layer and a porous medium layer, so the line separating them, do I define it as an interior or what to model heat transfer between the two layers??
thanks a lot

-mAx- May 26, 2010 01:24

Usually you don't need to define an edge (or surface) as interior, it is supposed to be done automatically, if your volumes are well connected.
I assume the "interface" between the flui domain is visible because you defined one domain as porous zone.
you can try to reset the fluid domain (delete the porous zone), and check if the line remains

engahmed May 26, 2010 11:18

Ok max, thanks for ur help :)

king lui May 20, 2011 07:28

Hey Max, I have also one question about the interface condition. Because I have a tube that is splitted in quarters and already meshed, now I thought i could use the interior condition so that the faces that split the tube are actually not considered in the Fluent analysis. But this doesn´t work as if I read my Gambit file with Fluent the following error occurs:

Cannot change interior:001 to interior because
there is only one adjacent cell thread.

Is it possible to solve this problem if the faces are specified as interfaces? I tried this but than there is an error if I do the check grid function in Flunet.

-mAx- May 20, 2011 08:22

post a sketch of your tube with interior etc...

king lui May 20, 2011 10:25

1 Attachment(s)
Here it is, the faces I was talking about are the horizontal and vertical planes within the tube.

-mAx- May 20, 2011 10:30

if the faces aren't connected, you cannot define them as interior, since they are interpreted as wall (outsurfaces from volume)
Either your connect them, with the possibility to lose the mesh from the connected volume, or you define the surfaces (which aren t connected) as interfaces.
Then in fluent you define the couple of interfaces.
First try to know if the volumes are connected (or not)

king lui May 20, 2011 10:38

Alright, this works and the error of the Fluent grid check is also gone if the interfaces are defined as couple.

Thank you very much for your help!!!

pbe_cfd February 5, 2013 07:07

Non-overlaping faces

How to define wall-BC for the faces which do not overlap on two surfaces when an interface between these two surfaces is created?


-mAx- February 5, 2013 07:18

do you have picture?

pulkitkbra22 April 9, 2013 06:41

HELLO Max, I m new to this forum as well to the use of Ansys Fluent.

I am having some problem in understanding the difference between a wall and an interface.

in my problem statement water is flowing in a pipe which put in the ground.heat from water flows to ground through the pipe. So, is there any need to define interface b/w fluid wall and pipe inner surface or pipe outer surface and ground inner surface??

I hope u got my question.If still it is not clear please do tell me I will elaborate it a bit. Please reply soon.

-mAx- April 9, 2013 07:56

may be it can help you

pulkitkbra22 April 10, 2013 12:01

interface boundary condition.
hey max,

i m still not able to solve the problem.
what i am suppose to do is to find out the temperature variation in a fluid as it flows through a pipe.Heat flows from the fluid to the surrounding environment.
Ansys 14.5 automatically creates a contact surface between fluid and pipe and names it interface. Is there any boundary condition I have to give there to get a proper solution??

-mAx- April 11, 2013 03:17

I let other users to reply since I am not a Ansys user

a.behravan May 22, 2013 10:45

Fluid Flow, Heat and Mass Transfer Boundary conditions at Porous/fluid Interface
Dear Max,

I am modelling a radiant heater which contains a porous media zone. This a counter diffusive reactor which means that the fuel enters from left side of the reactor and the air enters from right side of it. Combustion reaction occurs at the right side of it. The products of the reaction will leave the reactor from right side. So if I want to model the reactor I will have different B.Cs as follows:
for momentum eq.: right side of the reactor is Pressure-Outlet
for energy equation : righ side has natural convection+radiation+energy leaves the system due to mass transfer of hot products leaving the reactor
for mass transfer equation: the convective flux of reactants and products

If I could model the air region in the front of the reactor, I should consider the interface between right side of the reactor and air as interior or interface depending on mesh type. But with this B.C I cant model Radiation and probably natural convection. Please let me know if you can give me more information...

Thank you in advance.

-mAx- May 23, 2013 01:14

I don't know :rolleyes:
You would have more chance to get replies if you create your own thread

sasanghomi July 8, 2013 15:06

Hi Mazime ,

I want to create a good mesh around a missile and I want to generate a refinement mesh near the boundary of missile and mesh with bigger cells where is far from boundary of missile. So is it possible to define two regions mesh with Interface boundary condition between them?? (for generating two mesh with different density around the missile )

Thanks and best regards,

-mAx- July 9, 2013 01:00

no need to use interface, you can use size function for that

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