[Fierow97]

Hi everybody, I am new to fluent UDFs. My job is to define a heat source in a battery volume, extracting the data from a table which is then divided into time intervals in order to be more accurate when approximating this source data into a polynomial.
To define the source I set the UDF into time intervals using an if else if cycle. I obtained this UDF where in the first part I set an outside temperature monitor, then i set the source function. The problem I face is that starting from the 3rd interval the temperature has wrong values, increasing in an exagerated way. Where am I wrong??
Thanks in advance to anybody who will answer

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#include "udf.h"

real area_tot = 0;
real tsum = 0;
int i = 0;
FILE *qvol;

DEFINE_EXECUTE_AT_END(average_temp)
{
Domain *d;
face_t f;
real A[ND_ND];
real temper;
real area;
real tavg_real;
int ID = 10000;
int cell_id = 9995;
Thread *t;
cell_t c;
d = Get_Domain(1);
t = Lookup_Thread(d,ID);
c = Lookup_Thread(d,cell_id);


begin_f_loop(f,t) /*t identificato sopra*/
{
i++;
F_AREA(A,f,t);
area = NV_MAG(A);
temper = F_T(f,t);
area_tot += area;
tsum += temper;
}
end_f_loop(f,t)
tavg_real = F_UDMI(f,t,0) = tsum /( i * area_tot);

}

DEFINE_SOURCE(heat_source_else,c,t,ds,eqn)
{
real time = CURRENT_TIME - 20;
real source;
face_t f;
real tavg = F_UDMI(f,t,0);
begin_c_loop(c, t) /* loops over faces in a face thread */
{
if (time <= 80)
{
source = 1.293740341969334e+04 +
1.155185358507742e+03 * time -
2.379268980753591e+03 * tavg -
5.649970340744653e+01 * pow(time, 2) -
1.976396708411658e+01 * time * tavg +
1.752096173848799e+02 * pow(tavg, 2) +
1.339829964037692e+00 * pow(time, 3) +
6.257563010711130e-01 * pow(time, 2) * tavg +
2.835527245363084e-01 * time * pow(tavg, 2) -
6.547212742496961e+00 * pow(tavg, 3) -
1.372517572726491e-02 * pow(time, 4) -
1.426208700704884e-02 * pow(time, 3) * tavg +
7.545497774402981e-03 * pow(time, 2) * pow(tavg, 2) -
1.092233515427415e-02 * time * pow(tavg, 3) +
1.160103394950499e-01 * pow(tavg, 4) +
5.145914794527816e-05 * pow(time, 5) +
8.069157261724937e-05 * pow(time, 4) * tavg -
1.157443550354187e-05 * pow(time, 3) * pow(tavg, 2) -
5.689098345730353e-05 * pow(time, 2) * pow(tavg, 3) +
1.082901372206399e-04 * time * pow(tavg, 4) -
7.861770488630989e-04 * pow(tavg, 5);
}
else if (time > 80 && time <= 1560)
{
source = 3.572353433966986e+04 +
1.504725560307832e+01 * time -
4.305741709837774e+03 * tavg -
3.007670621456760e-02 * pow(time, 2) +
1.859195732546453e-01 * time * tavg +
2.884657370568110e+02 * pow(tavg, 2) +
3.713674310102147e-05 * pow(time, 3) -
1.526458940539785e-04 * pow(time, 2) * tavg -
2.028220731966852e-03 * time * pow(tavg, 2) -
1.027481185720795e+01 * pow(tavg, 3) -
1.887603697296835e-08 * pow(time, 4) -
3.512652110128167e-07 * pow(time, 3) * tavg +
1.883092302028152e-05 * pow(time, 2) * pow(tavg, 2) -
2.304064723465128e-04 * time * pow(tavg, 3) +
1.783596586083186e-01 * pow(tavg, 4) +
2.833434262501215e-12 * pow(time, 5) +
2.156423741401386e-10 * pow(time, 4) * tavg -
6.701362245916121e-09 * pow(time, 3) * pow(tavg, 2) -
3.217842108648160e-08 * pow(time, 2) * pow(tavg, 3) +
2.145009790443847e-06 * time * pow(tavg, 4) -
1.197286765135389e-03 * pow(tavg, 5);
}
else if (time > 1560 && time <= 1900)
{
source = 9.531011471749905e+06 -
3.363916338547694e+04 * time +
3.331256457378804e+05 * tavg +
4.503208628648606e+01 * pow(time, 2) -
6.947718183443817e+02 * time * tavg -
1.327004912238531e+03 * pow(tavg, 2) -
2.816703307340135e-02 * pow(time, 3) +
3.968045984613180e-01 * pow(time, 2) * tavg +
9.723870943634603e+00 * time * pow(tavg, 2) -
1.288886842505804e+02 * pow(tavg, 3) +
7.980268082497785e-06 * pow(time, 4) +
1.071912314326167e-05 * pow(time, 3) * tavg -
1.263872195054982e-02 * pow(time, 2) * pow(tavg, 2) +
2.532290242144435e-01 * time * pow(tavg, 3) -
1.454134052575408e+00 * pow(tavg, 4) -
7.470693278106096e-10 * pow(time, 5) -
4.531503740743649e-08 * pow(time, 4) * tavg +
4.756817026485388e-06 * pow(time, 3) * pow(tavg, 2) -
1.298019551282745e-04 * pow(time, 2) * pow(tavg, 3) +
1.595715190293275e-03 * time * pow(tavg, 4) -
8.289107283507393e-03 * pow(tavg, 5);
}
else if (time > 1900 && time <= 2650)
{
source = 1.334556967592067e+05 +
1.364202357062836e+03 * time -
1.604028456958695e+05 * tavg -
2.946727748042327e+00 * pow(time, 2) +
3.266616064310093e+02 * time * tavg -
1.322310937086781e+03 * pow(tavg, 2) +
2.432675706044515e-03 * pow(time, 3) -
2.982415242081833e-01 * pow(time, 2) * tavg +
5.620745389958381e+00 * time * pow(tavg, 2) -
8.724593124214688e+01 * pow(tavg, 3) -
9.268854786566970e-07 * pow(time, 4) +
1.320652320957073e-04 * pow(time, 3) * tavg -
4.858031909644004e-03 * pow(time, 2) * pow(tavg, 2) +
1.155495186556525e-01 * time * pow(tavg, 3) -
7.673718590338964e-01 * pow(tavg, 4) +
1.333096487842449e-10 * pow(time, 5) -
2.162492986745797e-08 * pow(time, 4) * tavg +
1.081528976294556e-06 * pow(time, 3) * pow(tavg, 2) -
2.839762204484407e-05 * pow(time, 2) * pow(tavg, 3) +
1.455524895059615e-04 * time * pow(tavg, 4) +
2.722899274167420e-03 * pow(tavg, 5);
}
else if (time > 2650)
{
source = -4.095300318889147e+06 +
7.823847587495723e+03 * time -
1.043765737289807e+05 * tavg -
5.825576421889270e+00 * pow(time, 2) +
1.309094467134265e+02 * time * tavg +
5.390501339365486e+02 * pow(tavg, 2) +
2.146396857180939e-03 * pow(time, 3) -
6.645451890148453e-02 * pow(time, 2) * tavg +
3.745400361652057e-02 * time * pow(tavg, 2) -
2.129175105412379e+01 * pow(tavg, 3) -
3.903416990802825e-07 * pow(time, 4) +
1.446547355408757e-05 * pow(time, 3) * tavg +
4.847441274804268e-05 * pow(time, 2) * pow(tavg, 2) -
3.187304494343842e-03 * time * pow(tavg, 3) +
4.391172638049189e-01 * pow(tavg, 4) +
2.802566549093382e-11 * pow(time, 5) -
1.133194749454201e-09 * pow(time, 4) * tavg -
1.451245741925541e-08 * pow(time, 3) * pow(tavg, 2) +
8.615177289567311e-07 * pow(time, 2) * pow(tavg, 3) -
1.897745223176266e-05 * time * pow(tavg, 4) -
2.495312174754752e-03 * pow(tavg, 5);
}
ds[eqn] = 0;
return source;
}
end_c_loop(c, t)
}