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UDF problems - velocity profile

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Old   January 30, 2008, 07:47
Default UDF problems - velocity profile
  #1
Oli
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Hi everybody.

I'm trying to create a non uniform velocity profile at inlet ; the same as you can find it in the Fluent Docs.

The source code is

#include "udf.h"

DEFINE_PROFILE(x_velocity,thread,index)

{

real x[ND_ND];

real y;

face_t f;

begin_f_loop(f,thread)

{

F_CENTROID(x,f,thread);

y = x[1];

F_PROFILE(f,thread,index) = 30.0-30.0*(y*y)/(1.5*1.5)

}

end_f_loop(f,thread)

}

now i try to compile the source code

--> Define --> User Defined Functions --> Interpreted (as it is shown in the Fluent Docu)

But I always get the error : Error: /.../... : line 2 : syntax Error

Do i overlook something?

Fluent is running on a Linux operating system.

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Old   January 30, 2008, 17:15
Default Re: UDF problems - velocity profile
  #2
BG
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F_PROFILE(f,thread,index) = 30.0-30.0*(y*y)/(1.5*1.5)

You forgot the semi colon at the line end

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Old   January 31, 2008, 05:37
Default Re: UDF problems - velocity profile
  #3
Oli
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oh yes, thx

but there's still the same error ... other udf's (for example residence_time with DEFINE_SOURCE) are working without problems....
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Old   February 3, 2008, 06:13
Default Re: UDF problems - velocity profile
  #4
shehab abdelrahman
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hi try replace the (index) in line 2, with just(i)... best regards, shehab
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Old   September 30, 2013, 16:39
Default Velocity Profile
  #5
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Yunusrulz
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Hi, I want to keep velocity inlet in compressible flow.. since compressible flow allows mass flow inlet I kept same mass flow inlet profile... but it keeps changing as simulation progresses. so i wanna keep velocity inlet in a compressible flow problem.. but the simulation strucks some where.. it shows divergence error.. so is there any way to keep velocity inlet in compressible flow with pressure based solver and laminar flow ??
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Old   October 24, 2016, 05:51
Question UDF for inlet temperature
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mmunige is an unknown quantity at this point
Dear all

I have following UDF for inlet temperature, untill 1300s it takes correct values according to equation, but after 1300s values are higher and not accorrding to equation, like at 1301s it should have value of 405C but in simulation inlet temperature is 621C. I could not find the error in my UDF after lot of try. please check this and guide me
#include"udf.h"

DEFINE_PROFILE(inlet_temperature,thread,position )

{

face_t f;

begin_f_loop(f,thread)

{

real t = RP_Get_Real("flow-time");

if (t <=1300.0 )

{

F_PROFILE(f,thread,position) = 379.13 + 0.0005*t;

}

else if (1300.0 < t && t <= 1500.0 )

{

F_PROFILE(f,thread,position)= -1.04289036878969*pow(10,-10)*pow(t,6.0)+ 8.86126436853789*pow(10,-7)*pow(t,5.0)-3.13621260398811*pow(10,-3)*pow(t,4.0)+5.91804640375908*pow(t,3.0)-6.27969461279651*pow(10,3)*pow(t,2.0)+ 3.55273415252714*pow(10,6)*t - 8.37223405676245*pow(10,8);
}
else
{

F_PROFILE(f,thread,position) = -9.51538261322402*pow(10,-23)*pow(t,6) + 8.26192751387975*pow(10,-18)*pow(t,5)-2.85237398505875*pow(10,-13)*pow(t,4)+4.97518353700886*pow(10,-9)*pow(t,3)-4.58733775886876*pow(10,-5)*pow(t,2)+ 2.10251137071757*pow(10,-1)*t +3.57252192344954*pow(10,2);

}

}

end_f_loop(f,thread)

}
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Old   October 24, 2016, 11:38
Default
  #7
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pakk will become famous soon enough
You asked the same question in a different thread.
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