# surface reaction UDF

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 April 10, 2013, 23:45 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!

 April 11, 2013, 03:10 #2 Senior Member   Paritosh Vasava Join Date: Oct 2012 Location: Lappeenranta, Finland Posts: 725 Rep Power: 16 The *rr calculated is in order of 10^-8 , isnt that too low?

April 11, 2013, 03:33
#3
New Member

tjut-wx
Join Date: May 2009
Posts: 14
Rep Power: 10
Quote:
 Originally Posted by vasava The *rr calculated is in order of 10^-8 , isnt that too low?
I have adjust the accurance of the reaction rate, the order of 10^-8 can be displayed!

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