[RocketGme]

Hello everyone,

I'm having some trouble writing UDFs to define fluid transport properties. I can successfully read experimental values from an external matrix (i.e. as function of p,T) and I think I managed to define properties at each cell value through DEFINE_PROPERTY with an interpolation function.

However, importing the matrix inside the DEFINE_PROPERTY function results in an eccessive cost since at each iteration the matrix is re-opened.

So the idea is to write a DEFINE_ON_DEMAND to load the property matrix (putting it into memory once and for all), and then to write a DEFINE_PROPERTY to interpolate and find the correct value. I wrote the whole process in once .c file and then compiled it with the Fluent built-in compiler. As I do so, both the matrix and the property UDF seem to be correctly loaded, but as I apply the udf in the material log, Fluent crushes (stating "the f1 process could not be started").

My guess is that I'm not able to call the matrix generated in one function, into the other. I tried storing the variable (double**) globally and I'm quite sure I'm doing that wrong. I'm totally new to both C language and Fluent UDFs, so any help would be appreciated. Thank you!

I attach a summary of my code .c

#include "udf.h"
#include <stdio.h>
#include <stdlib.h>

/* global variables */

double* P; /*defining array*/
double* T; /*defining array*/
double** Var_rho; /*defining matrix*/

DEFINE_ON_DEMAND(read_density){

P = malloc(NP * sizeof(double*));
T = malloc(NT * sizeof(double*));
Var_rho=malloc(NT*sizeof(double*));
for(i=0;i<NT;++i)
Var_rho[i]=malloc(NP*sizeof(double));

.... code to open external files and store arrays and matrix ....

}

DEFINE_PROPERTY(DensityUDF, c, t){

.... code to interpolate and define property ....
(here I call something like rho11 = Var_rho[n][m] where Var_rho is the one defined in the previous function)

return rho;
}