UDF problems - velocity profile
 

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.

Re: UDF problems - velocity profile
 

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

You forgot the semi colon at the line end

Re: UDF problems - velocity profile
 

oh yes, thx

but there's still the same error :( ... other udf's (for example residence_time with DEFINE_SOURCE) are working without problems....

Re: UDF problems - velocity profile
 

hi try replace the (index) in line 2, with just(i)... best regards, shehab

Velocity Profile
 

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 ??

UDF for inlet temperature
 

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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