[NewFluent]

Hi,
I uses the Fluent 6.3.26 and when I want hooking (UDF DEFINE_ON_DEMAND) in " Execute on Demand " menu,This error occurs.

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: ()

in my UDF I want to Eliminate the values of negative pressures in Zone Fluid domain. can you guid me.

[Bruno Machado]

Originally Posted by NewFluent

Hi,
I uses the Fluent 6.3.26 and when I want hooking (UDF DEFINE_ON_DEMAND) in " Execute on Demand " menu,This error occurs.

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: ()

in my UDF I want to Eliminate the values of negative pressures in Zone Fluid domain. can you guid me.

if you post your UDF we might be able to help you.

[NewFluent]

this is my UDF
/*********************************************/
#include "udf.h"

/* ************************************************** ************/
DEFINE_ON_DEMAND(pressure_adjust)
{
/************************************************** *************/
Domain *domain;
Thread *t;
cell_t c; /* Define a cell variable */
face_t f; /* Define a cell face variable */
int ID=4; /* Integer “4” is the fluid domain number, */
real x[ND_ND];
domain=Get_Domain(1);
/************************************************** ********/
thread_loop_c(t,domain)
{
begin_c_loop(c,t)
{
if (C_P(c,t)<0) /* If the pressure within the fluid domain is smaller than 0 Pa, switch it
back to 0 Pa */
{C_P(c,t)=0;}
}
end_c_loop(c,t)
}
thread_loop_f(t,domain)
{
begin_f_loop(f,t)
{
if (F_P(f,t)<0)
{F_P(f,t)=0;}
}
end_f_loop(c,t)
}
}
/************************************************** *************/

[Bruno Machado]

Originally Posted by NewFluent

this is my UDF
/*********************************************/
#include "udf.h"

/* ************************************************** ************/
DEFINE_ON_DEMAND(pressure_adjust)
{
/************************************************** *************/
Domain *domain;
Thread *t;
cell_t c; /* Define a cell variable */
face_t f; /* Define a cell face variable */
int ID=4; /* Integer “4” is the fluid domain number, */
real x[ND_ND];
domain=Get_Domain(1);
/************************************************** ********/
thread_loop_c(t,domain)
{
begin_c_loop(c,t)
{
if (C_P(c,t)<0) /* If the pressure within the fluid domain is smaller than 0 Pa, switch it
back to 0 Pa */
{C_P(c,t)=0;}
}
end_c_loop(c,t)
}
thread_loop_f(t,domain)
{
begin_f_loop(f,t)
{
if (F_P(f,t)<0)
{F_P(f,t)=0;}
}
end_f_loop(c,t)
}
}
/************************************************** *************/

you are defining your fluid domain as 4 but you are looping it in all the domains, not only in this one. you can add an if like the following to your code, then it will loop it only in the zone ID 4.

if (Zone_ID ==4)

in addition to that, what is the physical meaning of a non negative pressure? any reason for that? can you explain a bit more of your problem?

[NewFluent]

Originally Posted by Bruno Machado

you are defining your fluid domain as 4 but you are looping it in all the domains, not only in this one. you can add an if like the following to your code, then it will loop it only in the zone ID 4.

if (Zone_ID ==4)

in addition to that, what is the physical meaning of a non negative pressure? any reason for that? can you explain a bit more of your problem?

This UDF considers the zone where the pressure is smaller than the ambient pressure (usually 0 Pa, gauge pressure) as the cavitation area.
this problems exists in the hydrodynamic lubrication (Journals and Thrusts Bearings).

can you execut this UDf for me in your PC , and look if you have this ERROR
thanks.

[masoud.ravan]

Hi
I have the same problem, then I found that the problem is [Get_Domain] by running the code line by line...but I don't know what is the problem with this function...!!!
Did you solve your problem?