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Jenny_W September 1, 2012 19:33

Mass Imbalance in Reaction Stoichiometry in FLUENT
Dear All
I'm simulating a simple chemical reaction HCl + NaOH ==> NaCl + H2O.

I create reaction mechanism files in CHEMKIN format and import them into FLUENT. However FLUENT shows "warning: mass imbalance in reaction-1 stoichiometry" and I am confused since the reaction is already balance.

Another problem is that along the centreline of my domain, the concentration of NaOH increases beyond the original concentration at the inlet. This is not realistic. The NaOH concentration should be lower than the concentration at the inlet because some of NaOH has been converted to the products.

I do not know what the problem is. If anyone has any idea or suggestion please kindly advise.
Thank you,

sir September 16, 2012 22:23

Same problem...
Hi Jenny..

I also got the same warning..I already check the stoichiometry; and it is balance..If you hv any idea, hope u don't mind to share...and i will struggle to find out the solution..

C u


Jenny_W September 17, 2012 05:54

Hi Sirly,
I'm sorry I still cannot find the solution to this. If I can solve the problem, I will let you know :)

epc1 September 17, 2012 11:57

Hello, ive had this problem sometimes in the past.

Id recommend to check the Molecular wieghts of the species involved in the reactions, in the materials panel.

Jenny_Wong September 18, 2012 11:01

I'll do that. Thank you very much Ernesto.

danielet82 October 28, 2013 08:32

Hello, I experienced the same problem and I couldn't initialize the domain and run the simulation. I checked the molecular weights of the species involved in the reaction and it can be initialized and it gives good convergence despite the fact that the same message appears.

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