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Species mass source

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Old   March 8, 2018, 13:46
Default Species mass source
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André
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Hi everyone.

I am dealing with a problem in which I have 1 velocity inlet, and 2 outlets downstream (like a T junction).

Upstream of the junction I have a species mass source which is being introduced into the flow.

I have a doubt regarding this problem, since when I look at the balance (in+out), it is very close to zero, however I would expect that the mass source would increase the mass flux at the outlets.

Is there any explanation for this? My thoughts are it is a passive scalar, and therefore only follows the flow, and does not add extra mass/volume. Is this plausible?

Thanks in advance!
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Old   March 9, 2018, 06:54
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Hi,
I suggest to let the transport equation converges with res<10-6 (if possible). It takes time for the species solution to propagate from the inlet through the domain (even in the steady state problems).

It is better to patch your domain with a reasonable value for the species after initialization and then run your problem.
You can check in different iterations to see if the outlet values are changing.
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Old   March 9, 2018, 10:13
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Thanks for the reply e_cfd, however it looks like adding species alone will not change the mass flux.

I tried adding a mass source of 11.3 kg/s and this imbalance shows when I sum the exit and inlet mass flows. The species injection I put was 0.12 kg/s, but before the mass imbalance was about an order of magnitude or two under 0.12, which is just probably due to numerical error.

Thanks anyway!
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