[Hank-]

Hello all,

I am trying to convert a serial UDF (which works fine in a single core) to work in a parallel environment (higher cores).

Here is the UDF in a single-core setting,

#include "udf.h"
#include "mem.h"
#include <stdio.h>
#include <math.h>

#define Q 60.e-06
#define e0 8.854e-12

// Define which user defined scalars to use
enum
{
phi, /* 0 - Electric potential*/
E, /* 1 - Electric field*/
Fdix, /* 2 - x-component Dielectrophoretic force*/
};

DEFINE_ADJUST(Adjust_fun, domain)
{
cell_t c;
face_t f;
real dp= 300.0e-09; //particle diameter
real ep = 4.6; //relative permittivity of particle
Thread *t; ;
real coff = M_PI*e0*pow(dp,3)*((ep-1)/(ep+2))*0.25/(2130.0*M_PI*pow(dp,3)/6.); // coefficienct in polarization force calculation

// Calculating Electric field E and the X-force Fdix from the potential (phi)
thread_loop_c(t,domain)
{
begin_c_loop(c,t)
{
C_UDSI(c,t,E) = NV_MAG(C_UDSI_G(c,t,phi));
if(C_UDSI(c,t,E)<=0.0)
C_UDSI(c,t,E)=0.0;
if(C_UDSI(c,t,E)>(Q/e0))
C_UDSI(c,t,E) = Q/e0;

C_UDSI(c,t,Fdix) = (2.*coff*C_UDSI(c,t,E)*(C_UDSI_G(c,t,E)[0]));
}
end_c_loop(c,t)
}

// Calculating the electrostatic force F on the face of the cell
thread_loop_f(t,domain)
{
begin_f_loop(f,t)
{
if(NULL !=THREAD_STORAGE(t, SV_UDS_I(phi)) && NULL != T_STORAGE_R_NV(t->t0,SV_UDSI_G(phi)))
F_UDSI(f,t,E)=C_UDSI(F_C0(f,t), t->t0, E);
if(NULL != THREAD_STORAGE(t,SV_UDS_I(E))&& NULL != T_STORAGE_R_NV(t->t0, SV_UDSI_G(E)))
{
F_UDSI(f,t,Fdix)=C_UDSI(F_C0(f,t), t->t0, Fdix);
}
}
end_f_loop(f,t)
}
}

The code calculates the electrostatic field in all the cells and faces of the domain from the potential values obtained from solving the scalar transport equation. The electrostatic force is then calculated from the electrostatic field.

So far I have tried looping over interior cells and principal faces only.
#include "udf.h"
#include "mem.h"
#include <stdio.h>
#include <math.h>

#define Q 60.e-06
#define e0 8.854e-12

// Define which user defined scalars to use
enum
{
phi, /* 0 - Electric potential*/
E, /* 1 - Electric field*/
Fdix, /* 2 - x-component Dielectrophoretic force*/
};

DEFINE_ADJUST(Adjust_fun, domain)
{
#if !RP_HOST
cell_t c;
face_t f;
real dp= 300.0e-09; //particle diameter
real ep = 4.6; //relative permittivity of particle
Thread *t; ;
real coff = M_PI*e0*pow(dp,3)*((ep-1)/(ep+2))*0.25/(2130.0*M_PI*pow(dp,3)/6.); // coefficienct in polarization force calculation

// Calculating Electric field E and the X-force Fdix from the potential (phi)
thread_loop_c(t,domain)
{
begin_c_loop_int(c,t)
{
C_UDSI(c,t,E) = NV_MAG(C_UDSI_G(c,t,phi));
if(C_UDSI(c,t,E)<=0.0)
C_UDSI(c,t,E)=0.0;
if(C_UDSI(c,t,E)>(Q/e0))
C_UDSI(c,t,E) = Q/e0;

C_UDSI(c,t,Fdix) = (2.*coff*C_UDSI(c,t,E)*(C_UDSI_G(c,t,E)[0]));
}
end_c_loop_int(c,t)
}

// Calculating the electrostatic force F on the face of the cell
thread_loop_f(t,domain)
{
begin_f_loop(f,t)
{
if PRINCIPAL_FACE_P(f,t)
{
if(NULL !=THREAD_STORAGE(t, SV_UDS_I(phi)) && NULL != T_STORAGE_R_NV(t->t0,SV_UDSI_G(phi)))
F_UDSI(f,t,E)=C_UDSI(F_C0(f,t), t->t0, E);
if(NULL != THREAD_STORAGE(t,SV_UDS_I(E))&& NULL != T_STORAGE_R_NV(t->t0, SV_UDSI_G(E)))
{
F_UDSI(f,t,Fdix)=C_UDSI(F_C0(f,t), t->t0, Fdix);
}
}
}
end_f_loop(f,t)
}
#endif
}

However, it did not result in correct values. The electrostatic field values and forces did not even converge.


I also tried just looping over the compute nodes over all the faces and cells as shown,

#include "udf.h"
#include "mem.h"
#include <stdio.h>
#include <math.h>

#define Q 60.e-06
#define e0 8.854e-12

// Define which user defined scalars to use
enum
{
phi, /* 0 - Electric potential*/
E, /* 1 - Electric field*/
Fdix, /* 2 - x-component Dielectrophoretic force*/
};

DEFINE_ADJUST(Adjust_fun, domain)
{
#if !RP_HOST
cell_t c;
face_t f;
real dp= 300.0e-09; //particle diameter
real ep = 4.6; //relative permittivity of particle
Thread *t; ;
real coff = M_PI*e0*pow(dp,3)*((ep-1)/(ep+2))*0.25/(2130.0*M_PI*pow(dp,3)/6.); // coefficienct in polarization force calculation

// Calculating Electric field E and the X-force Fdix from the potential (phi)
thread_loop_c(t,domain)
{
begin_c_loop(c,t)
{
C_UDSI(c,t,E) = NV_MAG(C_UDSI_G(c,t,phi));
if(C_UDSI(c,t,E)<=0.0)
C_UDSI(c,t,E)=0.0;
if(C_UDSI(c,t,E)>(Q/e0))
C_UDSI(c,t,E) = Q/e0;

C_UDSI(c,t,Fdix) = (2.*coff*C_UDSI(c,t,E)*(C_UDSI_G(c,t,E)[0]));
}
end_c_loop(c,t)
}

// Calculating the electrostatic force F on the face of the cell
thread_loop_f(t,domain)
{
begin_f_loop(f,t)
{
if(NULL !=THREAD_STORAGE(t, SV_UDS_I(phi)) && NULL != T_STORAGE_R_NV(t->t0,SV_UDSI_G(phi)))
F_UDSI(f,t,E)=C_UDSI(F_C0(f,t), t->t0, E);
if(NULL != THREAD_STORAGE(t,SV_UDS_I(E))&& NULL != T_STORAGE_R_NV(t->t0, SV_UDSI_G(E)))
{
F_UDSI(f,t,Fdix)=C_UDSI(F_C0(f,t), t->t0, Fdix);
}
}
end_f_loop(f,t)
}
#endif
}

the values do not match the results from a single core.

If anyone has any advice on how I can parallelize the UDF it would be of great help.

Thank you.

Hank