| Author | Message | ||
     Pascal Mosnier (p_mosnier) New member Username: p_mosnier Post Number: 2 Registered: 06-2005 |
Hi, I have natural diffusion between two regions. the problem is that the concentration of the variable is much greater in the center region, however I need to stop the variable diffusion in the outer region when it reaches a fixed value. Can I specify some kind of "if loop" in the boundaries conditions statements to do that ? Thanks in advance | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 696 Registered: 06-2003 |
As with all such effects, the place to start is to define carefully the real physical cause of the effect, and to be sure that this effect is correctly represented in the equations. One possibility that comes to mind is to use a CONTACT boundary between the two materials, and define a contact resistance that is very low until the outer region approaches the limit value, at which time the resistance increases to prohibit flow into the outer region. Use a smooth transition in the resistance, not an "IF", because an instantaneous jump can cause oscillations and slow running. |