# Surface reaction rate

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 December 15, 2007, 19:37 Surface reaction rate #1 Jon Guest   Posts: n/a Hello I want to model the O2 consumption on tissue surface as Michaelis-Menten equation, which states: R=Vm*Ci/(K+Ci) where Vm and K are constant and Ci is O2 concentration at the wall. In UDF (DEFINE_SR_RATE) Ci is defined by the molar concentration, therefore I have to convert it by multiplying the mass fraction of O2 by density and divide it by the molar weight, am I right?. I think the density must be defined at the centre not the face and in surface reaction is defined at the face, so how can I get the density at the cell centre? please help!!. Thanks

 December 17, 2007, 04:20 Re: Surface reaction rate #2 saghir Guest   Posts: n/a DEFINE_SR_RATE(user_rate,f,t,r,mole_weight,species _mf,rate) { dcell = C_R(F_C0(f,t),t->t0); *rate = /*kmol/m2-s */ }

 December 17, 2007, 10:23 Re: Surface reaction rate #3 Judd Guest   Posts: n/a Hi Saghir, Thanks, but can please explain more?. I tried to do like this: Thread *t0=t->t0; cell_t c0=F_C0(f,t); c1=C_R(c0,t0)*s1/mw1; but i got this msg "structure reference not implemented". Regards

 December 17, 2007, 10:43 Re: Surface reaction rate #4 saghir Guest   Posts: n/a you must write directly reel dcell; dcell = C_R(F_C0(f,t),t->t0); or Thread *t0; cell_t c0; c0 = F_C0(f,t); t0 = THREAD_T0(t); reel dcell; dcell = C_R(c0,t0);

 December 18, 2007, 00:46 Re: Surface reaction rate #5 suribabu Guest   Posts: n/a hi, can u explain about ur problem.

 December 19, 2007, 07:01 Re: Surface reaction rate #6 Judd Guest   Posts: n/a Thanks Saghir, i guess my problem is in the compiler, I will try to install a new one and try agin. many thanks, Hi Suribabu, my problem is mentioned in the first post here by Jon. Regards,