CFD Online Discussion Forums - Calling zone name, zone id and total pressure from Fluent scheme to UDF

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Calling zone name, zone id and total pressure from Fluent scheme to UDF

Hello,

I am calling zone id, zone name and total pressure from fluent scheme language to fluent UDF. I got appropriate zone id and zone name, but total pressure is not correct.

Following is the Scheme which I used;

(rp-var-define 'a () 'list #f)
(rpsetvar 'a ())
(for-each (lambda (t) (rpsetvar 'a (list-add
(rpgetvar 'a) (thread-id t))))
(get-all-threads))
(rpgetvar 'a)

(rp-var-define 'b () 'list #f)
(rpsetvar 'b ())
(for-each (lambda (t) (rpsetvar 'b (list-add
(rpgetvar 'b) (thread-name t))))
(get-all-threads))
(rpgetvar 'b)

(rp-var-define 'p() 'total-pressure #f)
(rpsetvar 'p())
(for-each ( lambda (t) (rpsetvar 'p (list-add (rpgetvar 'p) (thread-id t))))
(get-all-threads))
(rpgetvar 'p)

and following is the UDF;

#include "udf.h"
#include "var.h"

#ifdef STRUCT_REF
#define PRINT printf
#define thread-id-list a
#define thread-name-list b
#define total-pressure p
#else
#define PRINT CX_Message
#endif

DEFINE_ON_DEMAND(zoneid_zonename)
{
int i;
int a = RP_Get_List_Length("a");
int b = RP_Get_List_Length("b");
int p = RP_Get_List_Length("p");
PRINT("length of ID list: %dn", a);
PRINT("length of NAME list: %dn", b);
PRINT("length of PRESSURE list : %dn", p);

for (i = 0; i < a; i++)
{
PRINT("Zone ID: %d ...has the name %s... has the pressure = %d\n",
RP_Get_List_Ref_Int("a", i),
RP_Get_List_Ref_String("b", i),
RP_Get_List_Ref_Int("p",i));
}
}

Could anybody help me, what is wrong in UDF/scheme?

UDF for calculating volume-integral absolute pressure in all zones

As I understand, the problem was that you added (thread-id t) again to p.
I don't know about methods of obtaining total-pressure for ZONE in FLUENT, becuse it is quantity determined in each CELL.
However, we can calculate volume-integral of total-pressure in the zone directly in the UDF code.
Below is the code to calculate ABSOLUTE pressure in fluent (TOTAL+OPERATING) because it is more informative, then total pressure.
To calculate total pressure (relative), just exclude adding p_operating to the abs_pressure variable in the code, it would be:

Code:

abs_pressure+=C_P(c,c_thread)*C_VOLUME(c,c_thread);

In FLUENT, run scheme code:

Code:

rp-var-define 'a () 'list #f)

(rpsetvar 'a ())

(for-each (lambda (t) (rpsetvar 'a (list-add

                                                      (rpgetvar 'a) (thread-id t))))

          (get-all-threads))

(rpgetvar 'a)



(rp-var-define 'b () 'list #f)

(rpsetvar 'b ())

(for-each (lambda (t) (rpsetvar 'b (list-add

                                                        (rpgetvar 'b) (thread-name t))))

          (get-all-threads))

(rpgetvar 'b)

Compile the following UDF in C:

Code:

#include "udf.h"

#include "stdlib.h"

#include "var.h"



#ifdef STRUCT_REF

#define PRINT printf

#define thread-id-list a

#define thread-name-list b

#define abs-pressure p

#else

#define PRINT CX_Message

#endif



DEFINE_ON_DEMAND(zoneid_zonename)

{

    /*print thread id_s, thread_names and volume-integral values of abs-pressure for each thread*/

    int i;

    real p_operating=RP_Get_Float("operating-pressure");/*operating pressure*/

    int a = RP_Get_List_Length("a");

    int b = RP_Get_List_Length("b");

    PRINT("length of ID list: %d\n", a);

    PRINT("length of NAME list: %d\n", b);

    Domain *domain;

    domain = Get_Domain(1);/*assuming not multiphase flow, there is only one domain with number=1*/

    Thread *c_thread;



    int threads=0;

    thread_loop_c(c_thread, domain)

    {

    threads++;/*count cell threads number in our calculation domain*/

    }



    real* p = (double*)malloc(threads * sizeof(double*));/*array of volume-integral values of abs-pressure for each thread*/

    for (i = 0; i < threads; i++)

        p[i]=0.0;

    real abs_pressure;

    real total_volume;



    thread_loop_c(c_thread, domain)/*here we loop over all cell threads in domain*/

    {

     abs_pressure=0.0;

     total_volume=0.0;

     for (i = 0; i < a; i++)

         if (RP_Get_List_Ref_Int("a", i)==THREAD_ID(c_thread))

            {    

                cell_t c;

                begin_c_loop(c, c_thread)/*we should loop over all cells in the thread*/

                  {

                    abs_pressure+=(C_P(c,c_thread)+p_operating)*C_VOLUME(c,c_thread);

                    total_volume+=C_VOLUME(c,c_thread);

                  }                         

                end_c_loop(c, c_thread)

                abs_pressure/=total_volume;

                p[i]=abs_pressure;

                break;

            }

    }



    for (i = 0; i < a; i++)

    {

        PRINT("Zone ID: %d ...has the name %s... has the pressure = %f\n",

        RP_Get_List_Ref_Int("a", i),

        RP_Get_List_Ref_String("b", i),

        p[i]);

    }

    free(p);

}

You will obtain the volume-integral of absoulte pressure for each cell zone.

You can compare the values with

Code:

report/volume-integrals/vol-avg

values for each cell zone of abs-pressure, and they agree.

Thank you very much for your reply
:):)