Hello,
I am a new user of Molflow+. I encountered an issue during simulation: when setting the outgassing rate for a cavity, the simulation results differ by more than a hundred times when using “outgassing” and “outg/area” respectively. Why is this the case? Theoretically, the results should be consistent, shouldn’t they?
Intended behavior:
Outgassing/area * selection area = total outgassing
See here for exact meaning: Facet parameters - MolFlow / SynRad documentation
Do you get something different than expected?
Yes, I conducted simulations by setting the total outgassing rate and the outgassing rate per unit area separately, and obtained results with huge differences. Moreover, when setting the outgassing rate per unit area, the total outgassing rate calculated by the software was the same as the one I calculated; the only difference was that the results varied due to the use of “outgassing” and “outgassing per area” respectively.
Hi there! 
I work with Marton on MolFlow development, so I will jump in to help!
I tried the outgassing vs outgassing/area on a simple geometry and could not reproduce the problem. Could you please send us the examples you are working with? Ideally, send the “outgassing” and “outgassing/area” examples as two separate molflow zip files. Also, please tell us what results you are expecting and what results you get.
Thank you!
Petar
Hello, I have now figured out that the issue should be with the computer. After switching to a new computer, I no longer encounter this problem. As a novice, I would also like to ask some questions regarding operations: Can MOLFLOW obtain the dynamic process of vacuum pumping, or can it only obtain the steady-state process? Additionally, can it display the conductance size or effective pumping speed of the pipeline?
Yes, see tutorial about conductance:
MolFlow+ webinar - MolFlow / SynRad documentation (scroll to conductance Part 1).
Molflow can simulate dynamic processes in its time-dependent mode, up to a few minutes. For long-term processes, where the surface parameters, such as outgassing, change, we recommend other tools.
Hello, may I ask if the dynamic process can be used to simulate and derive the time required to go from the initial pressure to the target pressure? If yes, where can this part of the operation be performed?
Hello,
It’s better to wait for Marton or Roberto for a more precise answer, but when using the time-dependent mode there is the evolution plotter feature. It allows you to see how facet properties, including pressure, change with time. You can read more about it here.
I hope this helps! Otherwise, as I mentioned, one of my more experienced colleagues will provide a better answer.
You can see a pumpdown example here: