Print data from UDF to txt file
 

Hi everybody,
I am writing an UDF in order to update the contact angle between droplet phases of a droplet impacting a wall.
The UDF seems to do not work properly, so I tried to print in a txt file the informations I ned, but the the UDF does not print anything. Does anyone know what can be the problem? Is there a specific folder where I Should save the txt file?

PS if anyone has some other idea for the UDF, please share :)
Thank you all :)

My UDF is this
#include "udf.h"
double contact_line_position=0;
double time=0;
double dynamic_contact_angle=15.0;
double contact_velocity=0;
FILE *file_export;
double sum=0.0,R;

DEFINE_ADJUST(Contact_Angle_Update, domain)
{
Thread *thread = Lookup_Thread(domain, 12);
Thread **pt = THREAD_SUB_THREADS(thread);
cell_t cell;
face_t f;
real x[ND_ND];
double max_x=0;
FILE *file_export_2;
int n;
sum=0.0;

begin_c_loop_all (cell,pt[1])
{
if(C_VOF(cell,pt[1])!=0)
{
C_CENTROID(x,cell,pt[1]);
//printf("## x=%f y=%f z=%f vof=%f\n",x[0],x[1],x[2],C_VOF(cell,pt[1]));
if(x[1]>max_x)
max_x=x[1];
}
sum+=C_VOF(cell,pt[1]);
}
end_c_loop_all (cell,pt[1])

R=sqrt(sum*1.0e-08/M_PI);
printf("max_x=%f R=%f contact_velocity=%f time=%f dynamic_contact_angle=%f sum=%f\n",max_x,R,contact_velocity,time,dynamic_co ntact_angle,sum);

contact_velocity= (R-contact_line_position)/(RP_Get_Real("flow-time")-time);
contact_line_position = R;
time=RP_Get_Real("flow-time");

if(contact_velocity>=0)
dynamic_contact_angle= (120.0*M_PI/180.0) ;
else
dynamic_contact_angle= (65.0*M_PI/180.0) ;


file_export = fopen("file_export.txt", "a+");
fprintf(file_export,"max_x=%f R=%f contact_velocity=%f time=%f dynamic_contact_angle=%f\n",max_x,R,contact_veloci ty,time,dynamic_contact_angle);
fclose(file_export);


file_export_2 = fopen("file_export_2.txt", "a+");
fprintf(file_export_2,"max_x=%f R=%f contact_velocity=%f time=%f dynamic_contact_angle=%f\n",max_x,R,contact_veloci ty,time,dynamic_contact_angle);
fclose(file_export_2);

}

DEFINE_PROFILE(Contact_Angle_Set_Profile,t,i)
{
face_t f;
begin_f_loop(f,t)
{
F_PROFILE(f,t,i) = dynamic_contact_angle;
}
end_f_loop(f,t)
}

if you are using fluent version 2019 and above you must make code in parallel

compile following code:

Hi Alexander, thank you for your help.
Yes I am using Fluent 19.2. At the program strating, I set it for use in parallele. But, when I try to load the new library with your UDF code, Fluent shows me this error:

Error: The UDF library you are trying to load (libudf) is not compiled for parallel use on the current platform (win64).\n\nImpossibile trovare il file specificato.
\n\nC:\Users\giova\Desktop\Prova UDF da forum\libudf\win64\2ddp_host\libudf.dll
Error Object: #f

Do you know what can be the mistake? Thank you for you help

Sorry, the error was due to the having saved the UDF with a name with spaces.
Now I loaded it, but still does not save the data in the txt files. :(
Do you have any idea?