age of air - transient calculation

July 11, 2008, 12:04

Hello, I need to calculate the age of air of the fluid exiting the domain in a transient calculation. Does the approach of setting up a passive scalar with source term = density work in transient as well?

July 14, 2008, 05:34

Yes it does. A quick 2D inviscid test case in STAR-CCM+ could give you the confidence.

Just remember that you might need to clip the source term where tau is large in order to get convergence of the passive scalar.

Typically in STAR-CCM+ the FF syntax for the source term might look like:

($PassiveScalar>10000)?0:$Density

July 11, 2008, 12:04	age of air - transient calculation	#1
roadracer Guest Posts: n/a	Hello, I need to calculate the age of air of the fluid exiting the domain in a transient calculation. Does the approach of setting up a passive scalar with source term = density work in transient as well?

July 14, 2008, 05:34	Re: age of air - transient calculation	#2
steve Guest Posts: n/a	Yes it does. A quick 2D inviscid test case in STAR-CCM+ could give you the confidence. Just remember that you might need to clip the source term where tau is large in order to get convergence of the passive scalar. Typically in STAR-CCM+ the FF syntax for the source term might look like: ($PassiveScalar>10000)?0:$Density

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