[zhouxman]

Hi,everybody,
how to determine the C0 and C1 on interior wall in fluent UDF?

[A CFD free user]

Originally Posted by zhouxman

Hi,everybody,
how to determine the C0 and C1 on interior wall in fluent UDF?

Dear Friend,

c0 = F_C0(f,t) and c1 = F_C1(f,t) are actually two macros are used to access to adjacent cell thread for faces (walls or interior). For wall faces, only c0 is available; however, for interior faces both c0 and c1 can be accessed via the right-hand rule. To determine the c0 and c1 thread on interior faces, you need to find the area normal vector. The cells out of which the area normal vector is pointing to is defined as c0 thread and the ones into which the area normal vector is pointing to is called c1 thread. So to get the right c0 and c1, first you should get the pertinent face thread using face look_up macro ant then employ the right-hand rue. To make it clear, see the schematic in attachment.

I hope it helps

[zhouxman]

Originally Posted by A CFD free user

Dear Friend,

c0 = F_C0(f,t) and c1 = F_C1(f,t) are actually two macros are used to access to adjacent cell thread for faces (walls or interior). For wall faces, only c0 is available; however, for interior faces both c0 and c1 can be accessed via the right-hand rule. To determine the c0 and c1 thread on interior faces, you need to find the area normal vector. The cells out of which the area normal vector is pointing to is defined as c0 thread and the ones into which the area normal vector is pointing to is called c1 thread. So to get the right c0 and c1, first you should get the pertinent face thread using face look_up macro ant then employ the right-hand rue. To make it clear, see the schematic in attachment.

I hope it helps

dear,
thanks for your reply!
as show in your schematic , is it means the c0 and c1 are fixed as shown in your schematic? how about the THREAD_T0 and THREAD_T1 ?

best regard

[zhouxman]

Originally Posted by A CFD free user

Dear Friend,

c0 = F_C0(f,t) and c1 = F_C1(f,t) are actually two macros are used to access to adjacent cell thread for faces (walls or interior). For wall faces, only c0 is available; however, for interior faces both c0 and c1 can be accessed via the right-hand rule. To determine the c0 and c1 thread on interior faces, you need to find the area normal vector. The cells out of which the area normal vector is pointing to is defined as c0 thread and the ones into which the area normal vector is pointing to is called c1 thread. So to get the right c0 and c1, first you should get the pertinent face thread using face look_up macro ant then employ the right-hand rue. To make it clear, see the schematic in attachment.

I hope it helps

dear,
how to determine the 'area normal vector'

[pakk]

To answer your question, it would help what you mean with "determine".

Do you want to know how to calculate the area normal vector in a script?
Or do you want to know what "area normal vector" means?
Or something else?

[zhouxman]

Originally Posted by pakk

To answer your question, it would help what you mean with "determine".

Do you want to know how to calculate the area normal vector in a script?
Or do you want to know what "area normal vector" means?
Or something else?

Dear pakk，
I want to know how to calculate the area normal vector in a script and the means of "area normal vector" .
Thanks

[pakk]

Probably the words "area normal vector" did not appear out of nowhere into your brain. You must have read it somewhere.

In fact, the only place I know where these words are used is in the Fluent manual. So I suggest you look there.

[Morteza60]

Hello all

I would like to know what is the functionality of THREAD_SHADOW(t) macro? I have searched little bit but i did not find any useful information. Can anybody demonstrate above macro in a UDF?

[pakk]

If you have a shadow wall in your simulation (an internal interface between a solid volume and a fluid volume), then in Fluent's internal storage, these are to boundaries:
* The solid-to-fluid boundary, as seen from the solid
* The fluid-to-solid boundary, as seen from the fluid

If, in a UDF, face thread "ft" refers to a solid-to-fluid boundary, then THREAD_SHADOW(ft) refers to the corresponding fluid-to-solid boundary.
If, in a UDF, face thread "ft" refers to a fluid-to-solid boundary, then THREAD_SHADOW(ft) refers to the corresponding solid-to-fluid boundary.
If, in a UDF, face thread "ft" does not refer to one of these two boundaries, then THREAD_SHADOW(ft) is NULL.

[Morteza60]

Thank you very much pakk

Could you please make an example of fluid-solid domain? the solid domain should be part of simulation and don't necessary have to be a wall. am I right?
like gas in vicinity of porous media?

[Jasonf]

Hi everyone!
I am also wondering how to determine the macros of adjacent cells, F_C0 and F_C1, on an interior wall (interface between fluid and solid zones) as illustrated in Fig. I heard of the right-hand law, but I do not know how to use it. Is there any simple way to solve this problem?
Thanks for any help!