CFD Online Discussion Forums - Problems in the UDF for DPM erosion

Hi, I am using DEFINE_UDF_EROSION to compute the deposition rate in the wall.

However, there are several codes in the UDF I could not understand. Could you help me for this?

1, It has defined for the 'WALL_CONDITION =2' in the UDF code. So, how could the wall condition=1 or 0??

2, I have shown all codes that contain 'WALL_CONDITION' underneath.

3, I don't understand what does 'WALL_CONDITION' mean? Is it come from the settings in the fluent or is it come from the computation results in the fluent?

4, The author explained what 0, 1,2 mean in the code
/* 0 for none stick new wall
1 for old wall that has deposit on and use the T_melt_wall given above
2 for old wall that has deposit on and the T_melt_wall will calculated as a function of the compositions of wall deposition using the same equations as for particles*/

Any help would be appreciated. Thanks in advance.

Code:

/*Wall sticking condition*/



#define WALL_CONDITION 2        

       eta3 = 0;

        if (WALL_CONDITION == 1)  /* what does wall condition==1 mean? */

        {

                if (F_T(f,t) > T_shift_wall)

                        eta3 = 1;

        }



        if (WALL_CONDITION == 2) /* what does wall condition==2 mean? */

        {

                T_shift_wall = F_T(f,t);

                m = 0.00835 * SiO2 + 0.00601 * Al2O3 - 0.109;

                c = 0.0415 * SiO2 + 0.0192 * Al2O3 + 0.0276 * Fe2O3 + 0.016 * CaO - 3.92;

                y = pow(10, 7) * m / T_shift_wall + c;

                muw = pow(10, y) / 10;

                

                if ((F_T(f,t) <= T_shift_wall) && (muw <= muc))

                {

                        eta3 = 1;

                }

        }



        if (WALL_CONDITION == 0) /* what does wall condition==0 mean? */

        {

                eta3 = 0;

        }