would you please send me a source.c code of UDF for 3D velocity inlet to cylinderical geometry really iam spent long time but i failed to write correct one thanks alot in avance sihat e mail sihatt2002@yahoo.com

wat is ur flow direction and inlet condition? normal to surface or only z velocity or what? and what type of boundary profile you expect at inlet?

Regrads Rizwan

thanks alot for your reply Mr. Rodwam, the flow direction is in the x-direction and the inlet is parabolic inlet velocity and here i have to use parabolic velocity equation to write the code and i try this alot but i fail to write correct code ,in fluent there is an example for parabolic inlet velocity for 2D flow but for me iwant this for 3D so i need your help thanks again sihat

send me the code u have wrote. il complete it. Regards Rizwan

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this is my code which is not give me the correct answer that iam using initial parabolic velocity inlet for 3D cylinderical geometry thanks in advance Mr. Rizwan

#include "udf.h"

DEFINE_PROFILE(inlet_x_velocity,thread,position) {

real x[ND_ND];

real y,z;

face_t f;

begin_f_loop(f,thread)

{

F_CENTROID(x,f,thread);

y=x[0];

z=x[2];

F_PROFILE(f,thread,position)=0.55-.0.55*pow(z+Y,20)/pow(0.05,20)*0.55;

}

end_f_loop(f,thread);

}

what is the size of ur pipe, diameter and max velocity?

0.55-.0.55*pow(z+Y,20)/pow(0.05,20)*0.55;

0.55 = max inlet velocity the flow is in the x-direction y-direction =the radial direction z-direction =the angular direction

annd this is the profile witen in the fluent manual 0.55-.0.55*pow(z+Y,20)/pow(0.05,20)*0.55;

so please help to write correct inlet parabolic velocity for 3D cylinderical geometry sihat

Have a look at this function. You should define in your header (or at the beginning of your file) FLOW_DIRECTION (1 for x direction, 2 for y direction and 3 for z direction) U0 (maximum velocity) and RP(pipe radius).

DEFINE_PROFILE(velocity_profile,thread,index) { #if !RP_HOST #if FLOW_DIRECTION==1

real x[ND_ND]; /* this will hold the position vector */

real y,z;

face_t f;

/* loops over all faces in the thread */

begin_f_loop(f,thread)

{

F_CENTROID(x,f,thread);

y = x[1];

z = x[2];

F_PROFILE(f,thread,index) = U0*(1.0-(y*y+z*z)/(RP*RP));

}

end_f_loop(f,thread) #elif FLOW_DIRECTION==2

real y[ND_ND]; /* this will hold the position vector */

real x,z;

face_t f;

/* loops over all faces in the thread */

begin_f_loop(f,thread)

{

F_CENTROID(y,f,thread);

x = y[0];

z = y[2];

F_PROFILE(f,thread,index) = U0*(1.0-(x*x+z*z)/(RP*RP));

}

end_f_loop(f,thread) #elif FLOW_DIRECTION==3

real z[ND_ND]; /* this will hold the position vector */

real x,y;

face_t f;

/* loops over all faces in the thread */

begin_f_loop(f,thread)

{

F_CENTROID(z,f,thread);

x = z[0];

y = z[1];

F_PROFILE(f,thread,index) = U0*(1.0-(x*x+y*y)/(RP*RP));

}

end_f_loop(f,thread) #else

Error("FLOW_DIRECTION should be 1, 2 or 3"); #endif /* FLOW_DIRECTION */ #endif /* RP_HOST */ }

thanks alot for your help but i have alittle bead confusion because i try so many but it give massage you have prase error in line 1 my question can you Mr Bogdan give me the typically what i must write to have corrct code if my flow is in x-ditection of 3D cylinder radius=0.55 max velocity=3.2m/s thanks alot sihat

so a minimum file should be like this:

#include "udf.h"

#define U0 3.2

#define RP 0.55

#define FLOW_DIRECTION 1 /*for x direction*/

then the function previous posted.

Hope this helps, Bogdan

i want u please to help me how to write this function correctely to complet the code to be interpreted in fluent because i try so many times and it give massage error prase lin 23 in this function line that means it is not written correctely. so please help if u have experience. the function is:

V = 0.55[(1-(z+y)/(0.6)]^20 thanks alot in advance sihat