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Macros for yplus, ystar, Ustar

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Old   August 23, 2011, 11:01
Default Macros for yplus, ystar, Ustar
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Hello,

I want to access the macro for yplus, ystar and Ustar in Fluent in my udf.
Does anyone know these macros? I am looking for a macro similar like C_R(c,t) to access the density in a cell.

Thanks in advance,
Seppl

Hello, I found the solution for yplus and U_tau (=friction velocity?)

F_STORAGE_R(f,t,SV_WALL_YPLUS)
F_STORAGE_R(f,t,SV_WALL_YPLUS_UTAU)

Last edited by Seppl Huber; August 24, 2011 at 04:56.
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Old   September 29, 2011, 12:36
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hi,Seppl
Do you know how to define yplus in Custom field function or UDF? The yplus in Fluent is only on the wall. I want to get a X-Y plot of uplus verus yplus along the wall normal direction. Could you give some sugguestion.
Thanks a lot.
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Old   November 4, 2011, 04:44
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Hi Renli,

I guess you can calculate u* (and therefore y+) only near wall. Because by definition
u* = sqrt(shear stress/rho)

From this you can get shear stress only near wall.. right?.. if so it may not good representation to plot y+ along wall normal.

John
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Old   November 4, 2011, 11:33
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Quote:
Originally Posted by Seppl Huber View Post
Hello,

I want to access the macro for yplus, ystar and Ustar in Fluent in my udf.
Does anyone know these macros? I am looking for a macro similar like C_R(c,t) to access the density in a cell.

Thanks in advance,
Seppl

Hello, I found the solution for yplus and U_tau (=friction velocity?)

F_STORAGE_R(f,t,SV_WALL_YPLUS)
F_STORAGE_R(f,t,SV_WALL_YPLUS_UTAU)



Dear All

i want to write a udf that stores the yplus in a UDMI for using that and get the USTAR at the boundaries, i dont know how use SV_WALL_YPLUS_UTAU;
d = Get_Domain(1);

thread_loop_c(t,d)
{
begin_c_loop(c,t)
{

C_UDMI(c,t,1)=C_STORAGE_R(f,t,SV_WALL_YPLUS_UTAU);

}
end_c_loop(c,t)
}

could you please give me an idea about that please

thanks
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Old   November 5, 2011, 06:46
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Quote:
Originally Posted by Seppl Huber View Post
Hello,

I want to access the macro for yplus, ystar and Ustar in Fluent in my udf.
Does anyone know these macros? I am looking for a macro similar like C_R(c,t) to access the density in a cell.

Thanks in advance,
Seppl

Hello, I found the solution for yplus and U_tau (=friction velocity?)

F_STORAGE_R(f,t,SV_WALL_YPLUS)
F_STORAGE_R(f,t,SV_WALL_YPLUS_UTAU)
Hi Huber,

When i try use the said macros i got the following error.

Error:
FLUENT received fatal signal (ACCESS_VIOLATION)
1. Note exact events leading to error.
2. Save case/data under new name.
3. Exit program and restart to continue.
4. Report error to your distributor.
Error Object: ()

Could you please explain how to use them in udf, is it like
F_STORAGE_R(f,t,SV_WALL_YPLUS)[1]?? or any header file need to be included to access those macros??

Thanks
John
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Old   March 23, 2012, 01:57
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Ming Cai
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Quote:
Originally Posted by johnwinter View Post
Hi Huber,

When i try use the said macros i got the following error.

Error:
FLUENT received fatal signal (ACCESS_VIOLATION)
1. Note exact events leading to error.
2. Save case/data under new name.
3. Exit program and restart to continue.
4. Report error to your distributor.
Error Object: ()

Could you please explain how to use them in udf, is it like
F_STORAGE_R(f,t,SV_WALL_YPLUS)[1]?? or any header file need to be included to access those macros??

Thanks
John
Because it's totally wrong....
it loops all cell threads but the macro accesses face values....
In my case, I defined search algorithm which gives wall value to all cells perpendicular to it as roni mentioned. but i'm not sure if it's the right way though...
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