# surface reaction UDF

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 April 11, 2013, 02:47 surface reaction UDF #1 New Member   tjut-wx Join Date: May 2009 Posts: 14 Rep Power: 10 hey！i am modelling the surface reaction，the overal reaction equation：2O3 -> 3O2. and its reaction rate formular is: r = K*b*O3/(1+b*O3); my UDF code as follows： #include "udf.h" #define K 6.8586e-11 #define b 15296.9e3 DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr) { Thread *t0 = t->t0; cell_t c0 = F_C0(f,t); real o3 = yi[0]; real rho_w = 1.0, T_w = 300.0; T_w = F_T(f,t); rho_w = C_R(c0,t0)*C_T(c0,t0)/T_w; o3 *=rho_w/mw[0]; *rr = K*b*o3/(1+b*o3); } the problem is：after compile and hook the UDF，the calcucation results showed that the reaction rate on the defined surface was zero。is there anyone who can help me analyse where the problem is and how to solve it? thanks!

 January 7, 2014, 15:52 #2 New Member   Sebastian Join Date: Dec 2011 Posts: 5 Rep Power: 8 Good afternoon, excuse me, did you find a solution to your problem? I’m experiencing the same; I would appreciate greatly your help.

August 8, 2017, 12:06
Hello ! Isn't it too late????
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sang-joon
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Quote:
 Originally Posted by jeniuswx hey！i am modelling the surface reaction，the overal reaction equation：2O3 -> 3O2. and its reaction rate formular is: r = K*b*O3/(1+b*O3); my UDF code as follows： #include "udf.h" #define K 6.8586e-11 #define b 15296.9e3 DEFINE_SR_RATE(my_rate,f,t,r,mw,yi,rr) { Thread *t0 = t->t0; cell_t c0 = F_C0(f,t); real o3 = yi[0]; real rho_w = 1.0, T_w = 300.0; T_w = F_T(f,t); rho_w = C_R(c0,t0)*C_T(c0,t0)/T_w; o3 *=rho_w/mw[0]; *rr = K*b*o3/(1+b*o3); } the problem is：after compile and hook the UDF，the calcucation results showed that the reaction rate on the defined surface was zero。is there anyone who can help me analyse where the problem is and how to solve it? thanks!

I think that the problems may be in the definition of yi[] and mw[].
You must check the order of species in your mixture-template.

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