Two gas constants in WRF-LES

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chench
Posts: 4
Joined: Fri Jan 15, 2021 9:01 pm

Two gas constants in WRF-LES

Post by chench » Fri Jan 15, 2021 9:29 pm

Hi group,

I just recently start using WRF-LES to study buoyant plumes, so I think it is an ideal case.

To study buoyant plumes, we set up a heat-flux from z=0 entering the domains. But the inflow gas has gas constant R=488.92 which is not air, and I think the ambient in the domain is air with R_air=288. So I am wondering what are the physical mechanisms between the inflow and the ambient air?

What is the inflow gas being treated, a new second species, a passive scalar or still just air? Or what happen when the inflow mixes with the air? What R should I use for post-processing?

The input file is attached, our team made some changes to the code so the input file may have additional inputs. I just start learning WRF and I used to develop inhouse DNS.
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namelist.input
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Ming Chen
Posts: 1473
Joined: Mon Apr 23, 2018 9:42 pm

Re: Two gas constants in WRF-LES

Post by Ming Chen » Wed Jan 20, 2021 10:59 pm

Is this a standard WRF-LES? Where did you set R=488.92? I also find some namelist options that don't exist in standard WRF.
I guess you are not running the standard WRF-LES. Please let me know if I am wrong.
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chench
Posts: 4
Joined: Fri Jan 15, 2021 9:01 pm

Re: Two gas constants in WRF-LES

Post by chench » Fri Jan 29, 2021 6:54 am

Thanks for following up Ming. One of our team members add change the codes so the input file looks a bit different. However, I just want to know if the inflow set with a different gas constant how does WRF-LES calculate the physical properties like viscosity? Thanks.

Ming Chen
Posts: 1473
Joined: Mon Apr 23, 2018 9:42 pm

Re: Two gas constants in WRF-LES

Post by Ming Chen » Mon Feb 01, 2021 7:24 pm

The standard code does not have two gases or this plume option.
My guess is that this constant is used only in the density calculation and that this
gas is added as a tracer or scalar. SO it shouldn't affect viscosity, etc.
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