Dumb question about species fractions (reactingFoam)

pattim · August 24, 2020, 19:56

OK - I feel pretty confident about this but should ask - I have read around on this forum that reactingFoam wants mass fractions specified. But I wonder how the code handles the case of fractions not adding to 1.0. For instance, if N2 initial value is set throughout the domain with internalField, then part of the domain is overwritten with a volScalarFieldValue in setFieldsDict. I've noticed that these seem to add, and thus would be > 1.0. Is this correct?

clapointe · August 24, 2020, 20:55

In most cases transport equation is not solved for N2 -- it is simply treated as an inert component and is computed as (pseudo code) 1 - sum(all species). So the code will figure it out.

Caelan

August 24, 2020, 19:56	Dumb question about species fractions (reactingFoam)	#1
pattim Member Patti Michelle Sheaffer Join Date: Sep 2018 Posts: 55 Rep Power: 7	OK - I feel pretty confident about this but should ask - I have read around on this forum that reactingFoam wants mass fractions specified. But I wonder how the code handles the case of fractions not adding to 1.0. For instance, if N2 initial value is set throughout the domain with internalField, then part of the domain is overwritten with a volScalarFieldValue in setFieldsDict. I've noticed that these seem to add, and thus would be > 1.0. Is this correct?

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August 24, 2020, 20:55		#2
clapointe Senior Member Join Date: Aug 2015 Posts: 494 Rep Power: 14	In most cases transport equation is not solved for N2 -- it is simply treated as an inert component and is computed as (pseudo code) 1 - sum(all species). So the code will figure it out. Caelan