# Problems in the UDF for DPM erosion

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 January 23, 2014, 06:29 Problems in the UDF for DPM erosion #1 New Member   Happy_weekend Join Date: Jan 2014 Posts: 20 Rep Power: 3 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; }```