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-   -   How to ?: Chemical decompostion (http://www.cfd-online.com/Forums/phoenics/51120-how-chemical-decompostion.html)

Wolfgang Schmidt November 4, 2000 16:40

How to ?: Chemical decompostion
 
Hello,

I'm wondering how to set up a simple chemical decompostion of a first order type like C1->B, without any density changes and all is one phase flow without any temperature dependence of the reaction-rate. I was exploring the shareware version 1.5 and tried the simple chemical source model using the term COVAL(CHSO,C1,GRND7,0.0) in the Group 13 section and using RSG3=RSG4=1. I thought this should give a first order decompostion of species C1 to B. But I'm afraid that I'm not understanding the terms in the help file correctly. The use of the above mentioned terms should yield a reaction rate like dC1/dt=-rsg3*C1**rsg4=-rsg3*C1. When I used these terms in a 2D-laminar simulation, the reaction rate whas some orders of magnitude to small -even taking the laminar flow profile into account. An exponential decay of C1 should occure like C1_L=CIN*exp(-rsg3*L/UIN), where L is the axial coordinate and UIN,CIN are the inlet velocity, concentration. If anybody needs for some advice the q1 file I used , I would like to mail this file to him/her.

Thanks in advance

Wolfgang


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