# Reaction rate under multi phases

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 February 16, 2012, 21:34 Reaction rate under multi phases #1 New Member   kong Join Date: Sep 2011 Posts: 21 Rep Power: 14 I want to write a UDF about reaction rate using DEFINE_VR_RATE. #include "udf.h" DEFINE_VR_RATE(vol_reac_rate,c,t,r,wk,yk,rate,rr_t ) { real ci,prod; int i; prod=1.; for(i=0;in_reactants;i++) { ci=C_R(c,t)*yk[r->reactant[i]]/wk[r->reactant[i]]; prod*=pow(ci,r->exp_reactant[i]); } *rate=r->A*exp(-r->E/(UNIVERSAL_GAS_CONSTANT*C_T(c,t)))*pow(C_T(c,t),r->b)*prod*(1-C_VOF(c,t)); *rr_t=*rate; } here Thread *t pointer to cell thread on which the volumetric reaction rate is to be applied. 1-C_VOF(c,t) is the volume fraction of second phase. If there are more than two phases, how can i specify the variables of the phases which are not applied by the reaction rate. thank you

February 16, 2012, 21:58
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Quote:
 Originally Posted by kongl1986 I want to write a UDF about reaction rate using DEFINE_VR_RATE. #include "udf.h" DEFINE_VR_RATE(vol_reac_rate,c,t,r,wk,yk,rate,rr_t ) { real ci,prod; int i; prod=1.; for(i=0;in_reactants;i++) { ci=C_R(c,t)*yk[r->reactant[i]]/wk[r->reactant[i]]; prod*=pow(ci,r->exp_reactant[i]); } *rate=r->A*exp(-r->E/(UNIVERSAL_GAS_CONSTANT*C_T(c,t)))*pow(C_T(c,t),r->b)*prod*(1-C_VOF(c,t)); *rr_t=*rate; } here Thread *t pointer to cell thread on which the volumetric reaction rate is to be applied. 1-C_VOF(c,t) is the volume fraction of second phase. If there are more than two phases, how can i specify the variables of the phases which are not applied by the reaction rate. thank you
I think (c,t) is the mixture, if you want to get vof of second phase, you shoud first use THREAD_SUB_THREAD to get the thread of second phase, says t_second_phase. then get its vof by C_VOF(c,t_second_phase)

 February 16, 2012, 22:38 #3 New Member   kong Join Date: Sep 2011 Posts: 21 Rep Power: 14 as described in help manual, Thread *t pointer to cell thread on which the volumetric reaction rate is to be applied. So i think t is only the phase applied the reaction rate , not the mixture. I have tried Thread***pt*=*THREAD_SUB_THREADS(t); *Thread**tp*=*pt[0]; *Thread**ts*=*pt[1]; But fluent shows wrong. BTW, I should define the phase before DEFINE_VR_RATE or after it?

 September 7, 2012, 08:43 #4 New Member   Join Date: Jul 2012 Posts: 19 Rep Power: 14 hey friend did u find solution to your problem i m having the same problem i.e whether t pointer to thread passed as argument in DEFINE_VR_RATE is for mixture level or for that particular reactive phase ?

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