[nhattan121]

Hi there,
I got a problem

I try to simulating the change of temperature of 1 cell 18650, change with SOC (state of charge) and current discharge (i choose 1C). Battery cell is convection only.

I followed the one paper, and try to write a code to solve this equation:
Screenshot 2022-01-09 185918.png

Here is result i have: contour of temperature
269878958_458679472553530_7054665062281506130_n.png

Here is a link of paper which i followed.
https://www.researchgate.net/publica...-ion_batteries

This below is my code. i used in source term of battery material.

#include "udf.h"
#include "math.h"
#define I 1.0 /* this is discharge current, is constant*/ 
DEFINE_SOURCE(heat_gen_rate, cell, thread, dS, eqn)
{
    real temp = C_T(cell, thread);
    real real_time = CURRENT_TIME;
    real soc = 1-(real_time*1.897533e-4); /* i assumed total time from SOC 1 to SOC 0 is 5270 second, like a paper. */
    real q;
    real u;
    real a[5][5] = {{174.87,-4.2857,0.063921,0.00056216,2.2924e-6},
                    {-421.73,-11.846,0.65394,0.0074809,0.00002289},
                    {710.11,58.26,-1.8389,-0.007132,0.00007878},
                    {-483.23,-84.388,2.0758,-0.0029176,-0.0002021},
                    {130.58,37.67,-0.83495,0.003493,0.00010523}};
                    
    real b[6][6] = {{218.49,-6.7907,-0.026023,0.0042377,-0.0000666,3.2778e-7},
                    {-2064.3,53.454,0.53007,-0.029377,0.0002498,-1.9726e-7},
                    {7960.5,-181.44,-2.1533,0.064345,0.0003483,-8.6883e-6},
                    {-14556.0,306.86,3.5406,-0.036523,-0.0026742,0.00003051},
                    {12619.0,-251.06,-2.6282,-0.028271,0.0038013,-0.0000372},
                    {-4166.1,78.657,0.75196,0.025085,0.0016507,0.0000152}};
    real c[6] = {4.8,-13.93,2.042,32.81,-38.54,13.02};
    
    int i;
    int j;
    for (j=0;j<5;j++)
    {
        for (i=0;i<5;i++)
        {
            q=(a[i][j]*pow(soc,(i-1))*pow(temp,(j-1)));
        }
    }

    
    for (j=0;j<6;j++)
    {
        for (i=0;i<6;i++)
        {
            q=q+(a[i][j]*pow(soc,(i-1))*pow(temp,(j-1)));
        }
    }
    q=q*pow(I,2);
    
    
    for (i=0;i<6;i++)
    {
        u=(c[i]*pow(soc,(i-1)));
    }
    u=u*I*temp;
    
    q=q+u;
    dS[eqn]=0;
    return q;
}

i confused too about " dS[eqn] ". I dont know what it means, i just mimic from other user on google.

[nhattan121]

From temperature contour, i think the UDF code is wrong. I dont know where is error

If you see a reference paper, all matrix and equation are include in Part 2 of paper, specifically in part 2.2, 2.3, and 2.4.

Please help me.