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Best practices to transfer variable between two DEFINE_FUNCTION

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Old   June 28, 2020, 02:27
Default Best practices to transfer variable between two DEFINE_FUNCTION
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Arun raj.S
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Hello everyone,

I would like to know the best practices for transferring a variables between two define functions with UDM in parallel mode. Why is it so hard ? Most of the time I receive segmentation fault. What is the proper procedure when UDMs are used? Example, should i define memory first, initialize and then load UDF or I can load UDF and then initialize. I would like to learn the nuances as it is very depressing and boring when we get segmentation fault.
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Old   June 30, 2020, 00:35
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Alexander
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Quote:
Originally Posted by arunraj View Post
Hello everyone,

I would like to know the best practices for transferring a variables between two define functions with UDM in parallel mode. Why is it so hard ? Most of the time I receive segmentation fault. What is the proper procedure when UDMs are used? Example, should i define memory first, initialize and then load UDF or I can load UDF and then initialize. I would like to learn the nuances as it is very depressing and boring when we get segmentation fault.
sequence depends on your case and logic of UDF.
what are you trying to do?
Start with single-core
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Old   June 30, 2020, 00:55
Default THREAD_SHADOW and F_SHADOW for shadow velocity inlet
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Arun raj.S
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Dear Alexander,

Thank you for your reply. Indeed, I made a logical error. I would like to access the call face and thread of one velocity inlet inside another. I used tle=THREAD_SHADOW(tve); fle=F_SHADOW(fve,tve); for this purpose. le- liquid evaporator and ve - vapor evaporator. They are shadow to each other but velocity inlet boundary as I am simulating liquid-vapor interface in heat pipe where I need to assign radial velocity and temperature. I am receiving the following error.

D:\leonard validation\libudfaabvvvbcccddaa\src\pipe.c(19) : warning C4700: uninitialized local variable 'fve' used
D:\leonard validation\libudfaabvvvbcccddaa\src\pipe.c(125) : warning C4700: uninitialized local variable 'fve' used

Is there a workaround for this problem to access the cell face id and thread id of another shadow boundary (not wall)?

I have attached my UDF. your help would be greatly appreciated.

#include "udf.h"

Thread *tve;
Thread *tle;
Thread *t0;
Thread *t0_s;

DEFINE_INIT(my_init_udf,d)
{
#if !RP_HOST
face_t fve;
face_t fle;
cell_t c0;
cell_t c0_s;
{
begin_c_loop(c0,t0)
{
tve=Lookup_Thread(Get_Domain(1),20);
c0 = F_C0(fve,tve);
t0 = F_C0_THREAD(fve,tve);
C_UDMI(c0,t0,0) = 0.0;
Message("first udmi is %g\n", C_UDMI(c0,t0,0));
}
end_c_loop(c0, t0);
}

{

begin_c_loop(c0_s,t0_s)
{
tve=Lookup_Thread(Get_Domain(1),20);
tle=THREAD_SHADOW(tve);
fle=F_SHADOW(fve,tve);
c0_s = F_C0(fle,tle);
t0_s = F_C0_THREAD(fle,tle);
C_UDMI(c0_s,t0_s,1) = 0.0;
Message("first udmi is %g\n", C_UDMI(c0_s,t0_s,1));
}
end_c_loop(c0_s, t0_s);
}
# endif
}

DEFINE_ADJUST(pipe, domain)
{
#if !RP_HOST
face_t fve;
face_t fle;
cell_t c0;
cell_t c0_s;
real temp_cell_ve, press_cell_ve, rho_cell_ve;
real rho_cell_le;
real hfg = 2360000.0;
real R = 8314.0;
real M = 18.015;
real RR;
real s = 0.03;
real po = 101325.0;
real to = 373.0;
real ti = 324.7278;
real p_op = 13450.0;
real a1, a2, a3;
real mdot;
real pi;
real vel_ve, vel_le;

begin_f_loop(fve, tve)
{
tve=Lookup_Thread(Get_Domain(1),20);
tle=THREAD_SHADOW(tve);
fle=F_SHADOW(fve,tve);
c0 = F_C0(fve,tve);
t0 = F_C0_THREAD(fve,tve);
c0_s = F_C0(fle,tle);
t0_s = F_C0_THREAD(fle,tle);
temp_cell_ve = C_T(c0,t0);
press_cell_ve = C_P(c0,t0);
rho_cell_ve = C_R(c0,t0);
rho_cell_le = C_R(c0_s,t0_s);
RR = R/M;
pi = po*exp((hfg/RR)*((1/to)-(1/ti)));
a1 = (2.0*s)/(2.0-s);
a2 = 1/sqrt(2*M_PI*RR);
a3 = ((p_op+press_cell_ve)/sqrt(temp_cell_ve))-(pi/sqrt(ti));
mdot = a1*a2*a3;
vel_ve=mdot/rho_cell_ve;
vel_le=mdot/rho_cell_le;
C_UDMI(c0,t0,0)=vel_ve;
C_UDMI(c0_s,t0_s,1)=-vel_le;
Message("vel_ve is %g\n", C_UDMI(c0,t0,0));
Message("vel_le is %g\n", C_UDMI(c0_s,t0_s,0));
}
end_f_loop(fve, tve)
#endif
}

DEFINE_PROFILE(vaporside_velocity, t, i)
{
#if !RP_HOST
face_t fve;
face_t fle;
cell_t c0;
begin_f_loop(fve, tve)
{
tve=Lookup_Thread(Get_Domain(1),20);
c0 = F_C0(fve,tve);
t0 = F_C0_THREAD(fve,tve);
F_PROFILE(fve, tve, i) = C_UDMI(c0,t0,0);
Message("vel_ve profile is %g\n", C_UDMI(c0,t0,0));
}
end_f_loop(fve, tve)
#endif
}

DEFINE_PROFILE(liquidside_velocity, t, i)
{
#if !RP_HOST
face_t fve;
face_t fle;
cell_t c0_s;
begin_f_loop(fle, tle)
{
tve=Lookup_Thread(Get_Domain(1),20);
tle=THREAD_SHADOW(tve);
fle=F_SHADOW(fve,tve);
c0_s = F_C0(fle,tle);
t0_s = F_C0_THREAD(fle,tle);
F_PROFILE(fle, tle, i) = C_UDMI(c0_s,t0_s,1);
Message("vel_le profile is %g\n", C_UDMI(c0_s,t0_s,1));
}
end_f_loop(fle, tle)
#endif
}
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