# Reaction rate under multi phases

 Register Blogs Members List Search Today's Posts Mark Forums Read

 February 16, 2012, 22:34 Reaction rate under multi phases #1 New Member   kong Join Date: Sep 2011 Posts: 21 Rep Power: 7 Sponsored Links 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, 22:58
#2
Senior Member

Ji Junjie
Join Date: Feb 2010
Location: Shanghai, China
Posts: 109
Rep Power: 10
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, 23:38 #3 New Member   kong Join Date: Sep 2011 Posts: 21 Rep Power: 7 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: 7 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 ?

 Tags phase, reaction rate

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post error3361 Fluent UDF and Scheme Programming 0 March 4, 2011 16:49 NewKid OpenFOAM 18 January 20, 2011 17:55 elmcmaster FLUENT 0 October 11, 2010 09:37 Stefan H Fluent UDF and Scheme Programming 0 September 16, 2009 13:20 La S. Hyuck CFX 1 May 23, 2001 00:07