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 The information provided may be out of date.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.
Decreasing Concentration Problem
Posted Apr 17, 2012, 6:48 a.m. EDT Version 4.2a 1 Reply
Please login with a confirmed email address before reporting spam
Hello All,
I'm currently working on a project to model the concentration of certain defects during the growth of a certain crystal using the Transport of Diluted Species interface. I've encountered a problem and can't seem to find a way around it. The concentration of these defects grows gradually and then stops after a certain time. When this concentration stops growing it should be maintained constant through the rest of the simulation. However, when I model the concentration in a 1D plot, the concentration decreases as the crystal grows. I've uploaded a simplified version which shows the problem in a clearer manner, using a gaussian function and a constant velocity which should only move this function in the z-direction. Instead of only moving the function, it also decreases the numerical result. I've tried modifying the mesh, and the problem persisted. I believe that this is a numerical error, any help would be appreciated. Thanks.
--
Patricio Davila
I'm currently working on a project to model the concentration of certain defects during the growth of a certain crystal using the Transport of Diluted Species interface. I've encountered a problem and can't seem to find a way around it. The concentration of these defects grows gradually and then stops after a certain time. When this concentration stops growing it should be maintained constant through the rest of the simulation. However, when I model the concentration in a 1D plot, the concentration decreases as the crystal grows. I've uploaded a simplified version which shows the problem in a clearer manner, using a gaussian function and a constant velocity which should only move this function in the z-direction. Instead of only moving the function, it also decreases the numerical result. I've tried modifying the mesh, and the problem persisted. I believe that this is a numerical error, any help would be appreciated. Thanks.
--
Patricio Davila
Attachments:
1 Reply Last Post Apr 20, 2012, 7:04 a.m. EDT
Please login with a confirmed email address before reporting spam
Posted:
1 decade ago
Update: I tried solving the same simple problem with the convection diffusion PDE equation, and the results were more stable. However there was still a slight decrease in concentration. I believe this is a numerical error. Has anybody any idea on how to avoid this problem? Thank you.
--
Patricio Davila
--
Patricio Davila