Menu

Discussion Forum

New Discussion
Filter

Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.

Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.

the problem of reactions and domains

Posted Nov 13, 2014, 10:57 p.m. EST Low-Frequency Electromagnetics, Plasma Physics Version 4.4 3 Replies

Crane Cheng
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

I am learning to use COMSOL and I have a problem. For the 1-d discharge model, we use polygon to divide one domain into multiple domains, but how can I add different reactions to the different domains?
3 Replies Last Post Nov 17, 2014, 10:11 a.m. EST
Luke Gritter Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Nov 14, 2014, 1:27 p.m. EST
Crane,

Despite having editable "Domain Selection" boxes on the settings tab for each reaction, the software seems to require that all reactions are enabled on all plasma domains. You can get around this by setting the reaction rate to zero on any domains where you don't want the reaction to be active. To do this, use Variables nodes (under Definitions) to create a variable that is equal to one in the domains where the reaction is active and zero elsewhere. Then multiply the reaction rate by this variable.

--
Luke Gritter
AltaSim Technologies
Crane, Despite having editable "Domain Selection" boxes on the settings tab for each reaction, the software seems to require that all reactions are enabled on all plasma domains. You can get around this by setting the reaction rate to zero on any domains where you don't want the reaction to be active. To do this, use Variables nodes (under Definitions) to create a variable that is equal to one in the domains where the reaction is active and zero elsewhere. Then multiply the reaction rate by this variable. -- Luke Gritter AltaSim Technologies
Crane Cheng
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Nov 16, 2014, 9:02 p.m. EST
Dear Luke,
Thank you for your reply. But how to deal with the reactions that is from Cross Section Import? it seems that reactions that from Cross Section Import don't have the reaction rate option? is it possible that using a variable multiplied by the collision cross section data or Townsend coefficient data? it looks very inconvenient if a reaction has huge data.
Dear Luke, Thank you for your reply. But how to deal with the reactions that is from Cross Section Import? it seems that reactions that from Cross Section Import don't have the reaction rate option? is it possible that using a variable multiplied by the collision cross section data or Townsend coefficient data? it looks very inconvenient if a reaction has huge data.
Luke Gritter Certified Consultant
Send Private Message Flag post as spam

Please login with a confirmed email address before reporting spam

Posted: 1 decade ago Nov 17, 2014, 10:11 a.m. EST
Crane,

When the reaction rate is defined using cross sections or a lookup table, you can still use the same technique. Activate "Equation View" using the "Show" icon, and click on the Equation View sub-node that appears directly under the reaction you want to modify. Both the rate coefficient and the reaction rate are defined here, and you can modify either of these variables to achieve the desired effect.

--
Luke Gritter
AltaSim Technologies
Crane, When the reaction rate is defined using cross sections or a lookup table, you can still use the same technique. Activate "Equation View" using the "Show" icon, and click on the Equation View sub-node that appears directly under the reaction you want to modify. Both the rate coefficient and the reaction rate are defined here, and you can modify either of these variables to achieve the desired effect. -- Luke Gritter AltaSim Technologies

Note that while COMSOL employees may participate in the discussion forum, COMSOL® software users who are on-subscription should submit their questions via the Support Center for a more comprehensive response from the Technical Support team.

Suggested Content