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Hi,

I have been able to reproduce an issue where if I upload a SYN file to Molflow to set the desorption rates for facets, and then change the desorption rates to zero of some of these facets and others they will snap back to the imported rate.  In other words the facets seem to have a "memory" of the imported state and will tend to switch back to that rate.

I have been working around this by starting from scratch on Molflow models whenever I want to change which facets are driven by Synrad data.  But if you are getting high pressures in a region you think you have turned off PSD I'd recommend double checking outgassing rates to make sure they are doing what you want them to.

 

Tom

Submitted by Marton Ady 6 years ago

Hello Tom,

Sorry for the delay, I wanted to include screenshots in my reply but I was out of office.

It is indeed possible that there is a bug, but could you check one last thing (as for the moment I can't reproduce it)?

You say that "then change the desorption rates to zero of some of these facets and others"...

  • Does it mean that this happens only if you try to set the outgassing to zero at the same time for a mix of facets, some with dynamic outgassing information and some without?
  • How exactly do you "set to zero"? Do you use the "None" desorption option, or you assign the 0 value?

I'm asking these because outgassing for these facets are controlled at two different locations (which I admit is a bit confusing but space was too precious in the facet parameter panel):

2017-11-09 18_34_55-Molflow+ 2.6.59 64-bit (Oct 30 2017) [CH4 1000 A hrs 0_004 rough 2015 05 22.zip].png
This above is the general outgassing control - note that in this case the numbers are greyed out as dynamic outgassing defines the outgassing rate.

If you select a mixture of facets with and without dynamic outgassing, the textfields might become editable.

2017-11-09 18_34_59-Molflow+ 2.6.59 64-bit (Oct 30 2017) [CH4 1000 A hrs 0_004 rough 2015 05 22.zip].png
This is the Dynamic desorption panel of the advanced facet parameters.

The expected behavior is:

  • When you import Synrad outgassing data, selected facets (on whom the import process has an effect) will all have a dynamic outgassing. The "Use file" combobox will switch to "Use des. file", and themanually written outgassing values (normally not editable) on the right side will be ignored.
  • If you set Desorption to "None" on the right side, the facet shouldn't desorb (neither at a fixed rate nor dynamically)
  • If you have already imported dynamic outgassing data for the selected facet(s), but want to use manual values for outgassing, then you should switch the Use file combobox to "Use user values", which will tell Molflow to ignore the dynamic outgassing data and use your manually entered numbers instead:
    2017-11-09 18_45_29-Molflow+ 2.6.59 64-bit (Oct 30 2017) [CH4 1000 A hrs 0_004 rough 2015 05 22.zip].png
  • Once again, if you want to completely disable the outgassing, instead of writing '0' as outgassing value, you should select "None" as desorption.

Having described the expected behavior, does Molflow behave differently (which confirms that it's a bug)? Let me know, maybe even attach a simple example (a small part of the geometry is sufficient if you're working on sg confidential) and I'll investigate.

Thanks for your feedback!