Concentration modelling

September 1, 2003, 06:44

Hi

I am running a conparison between Star and CFX 5 for modelling dispersion of H2S gas leak.

I am a very confused about the results in Star. The source area is 1700 m2 and the mass flow of H2S is 0.007 kg/s. Vind speed is 2 m/s.

The model and mesh is build so that it is the same for both Star and CFX.

My question is what unit for the concentration of scalar in Star ?

How can I convert the concentration to ppm ?

I know the concentration is given as a mass fraction. But when doing a comparison I get 2.2e-06 kg/m3 (in CFX) at the monitor point, but a mass fraction of 0.08 in Star at the same point.

Any hints is welcome !

/Peter

September 8, 2003, 03:22

It's kg/kg for mass fraction... it's dimensionless.

September 1, 2003, 06:44	Concentration modelling	#1
Peter Guest Posts: n/a	Hi I am running a conparison between Star and CFX 5 for modelling dispersion of H2S gas leak. I am a very confused about the results in Star. The source area is 1700 m2 and the mass flow of H2S is 0.007 kg/s. Vind speed is 2 m/s. The model and mesh is build so that it is the same for both Star and CFX. My question is what unit for the concentration of scalar in Star ? How can I convert the concentration to ppm ? I know the concentration is given as a mass fraction. But when doing a comparison I get 2.2e-06 kg/m3 (in CFX) at the monitor point, but a mass fraction of 0.08 in Star at the same point. Any hints is welcome ! /Peter

September 8, 2003, 03:22	Re: Concentration modelling	#2
cjtune Guest Posts: n/a	It's kg/kg for mass fraction... it's dimensionless.

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