finite rate/eddy dissipation model

roukaia · January 2, 2012, 12:21

Hello Everyone,

Could someone inform me how to give input for the pre-exponential factor for a complex mechanism in Fluent? Do I need to convert it from gmol/cm3 to kgmol/m3 with the reaction order as powers or do I specify the value which is given in the literature. or should i keep them const as they are !!
my reaction is c10h22+15.5O2=10co2+11h2O

In the literature the Pre-exponential factor is given as values and all they say is it is consitent with units of concentration (gmol/cm3)^1-m-n where m and n are 1 for an elementary mechanism.

The other problem is that in Fluent when I use the value of Pre-exponential factor as it is (by default), it is working.
any help would be appreciated

Thank you.

Sixkillers · January 3, 2012, 02:39

Units of pre-exponential factor should be for Fluent in (kmol/(m^3 * s))^(1-n) (assuming the temperature exponent is zero), where n is an overall reaction order, which is for an elementary reaction sum of stoichiometric coefficients of reactants.

roukaia · January 3, 2012, 12:57

thank you for replying
does any one has these books

"simplified reaction mechanisms for oxidation of hydrocarbon fuels in flames" westbook uk and drayer FL 1981

"evaporation and combustion of sprays progress in energy and combu
stion sciences "
my mail is : roukaia16@yahoo.fr

January 2, 2012, 12:21	finite rate/eddy dissipation model	#1
roukaia Member Boudour Join Date: Oct 2011 Posts: 34 Rep Power: 14	Hello Everyone, Could someone inform me how to give input for the pre-exponential factor for a complex mechanism in Fluent? Do I need to convert it from gmol/cm3 to kgmol/m3 with the reaction order as powers or do I specify the value which is given in the literature. or should i keep them const as they are !! my reaction is c10h22+15.5O2=10co2+11h2O In the literature the Pre-exponential factor is given as values and all they say is it is consitent with units of concentration (gmol/cm3)^1-m-n where m and n are 1 for an elementary mechanism. The other problem is that in Fluent when I use the value of Pre-exponential factor as it is (by default), it is working. any help would be appreciated Thank you.

January 3, 2012, 12:57	need books	#3
roukaia Member Boudour Join Date: Oct 2011 Posts: 34 Rep Power: 14	thank you for replying does any one has these books "simplified reaction mechanisms for oxidation of hydrocarbon fuels in flames" westbook uk and drayer FL 1981 "evaporation and combustion of sprays progress in energy and combu stion sciences " my mail is : roukaia16@yahoo.fr

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January 3, 2012, 02:39		#2
Sixkillers Member Join Date: Nov 2011 Location: Czech Republic Posts: 97 Rep Power: 14	Units of pre-exponential factor should be for Fluent in (kmol/(m^3 * s))^(1-n) (assuming the temperature exponent is zero), where n is an overall reaction order, which is for an elementary reaction sum of stoichiometric coefficients of reactants.