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-   -   Energy balance (http://www.cfd-online.com/Forums/fluent/33045-energy-balance.html)

Eric February 16, 2004 11:30

Energy balance
 
Hi,

I'm simulating gas combustion in a rotary kiln using the two-step eddy dissipation model. When I report/flux/total energy, to do an energy balance I get strange values.

My inlet values are negative and my outlet are positive. Also, I'm getting a much higher outlet value than I'm putting in.

I know this isn't a lot of information but can anyone tell me what I'm doing wrong? I'm following the tutorial 'Using the Non-Premixed Combustion Model'. I know this is has two phase combustion but I think the method is the same, may be I'm wrong??

Regards

Eric

cg February 17, 2004 20:33

Re: Energy balance
 
Fluent reports the total enthalpy (chemical, which is -ve, plus thermal, which is +ve). So, it is possible to have -ve enthalpy going in and +ve enthalpy coming out. Since enthalpy is relative, this should not matter. However, energy must balance - make sure that your energy and species URFs are 1, or nearly 1.


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