Re: [sparta-users] Fix Ambipolar Question

[Runco, J. J C. U. A. AFIT/E. <Joh...@af...>]

Chonglin/Steve,


I am currently still getting electron densities higher than the experimental data indicates (about 3 orders of magnitude). I think I am coding the fix ambipolar correctly, but was hoping to get a second pair of eyes on it to see if I was missing anything. Attached is my input dec. Highlighted in yellow are the lines that have to do with the fix ambipolar commands. I took the manual's suggestions as well and made 2 different mixtures, one with the electron and one without. I used a fix in/emit for the mixture without the electrons, and subsequently a collide command for a mixture with all the species.


Mistakes that I think are possible:

1. incorrect coding for the creation of two different groups (ion and electron) within the mixture containing all species...as the Sparta manual suggests?:

mixture air_wo_ID NO+ e group self


I am currently trying to run a job using two separate lines to distinguish the electron and ion (NO+) within the group that contains all the species:

mixture             air_wo_ID NO+ group ion_ID
mixture             air_wo_ID e group elec_ID


2. not varying the initial electron velocity used in the mixture command seen below? (don't think this is the issue due to the air.species and air.vss and air.tce files, but it came to mind).
species             air.species N2 O2 N O NO NO+ e
mixture             air_wo_ID N2 O2 N O NO NO+ e vstream 7650. 0. 0. temp 196.7

Appreciate the help,
John
Sparta User



________________________________
From: Chonglin Zhang <zha...@gm...>
Sent: Thursday, October 11, 2018 2:05 PM
To: Runco, John J Capt USAF AETC AFIT/ENY
Cc: spa...@li...
Subject: Re: [sparta-users] Fix Ambipolar Question

Yes, if you are modeling electron density, then you need to use the "fix ambipolar" command, together with "collide_modify" command.

You will need to do something like this:

collide_modify   vibrate smooth  ambipolar yes        # active the ambipolar approximation for ionization reactions.
fix  ID  ambipolar   e NO+ N+ O+ N2+ O2+              # set which species is electron, which species are ions; ID is the fix id number.


Thanks!
Chonglin

On Thu, Oct 11, 2018 at 1:42 PM Runco, John J Capt USAF AETC AFIT/ENY <Joh...@af...<mailto:Joh...@af...>> wrote:
If I am looking to verify electron densities, would accuracy also depend on incorporating the fix ambipolar command?


Thanks,

John Runco




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