| Author | Message | ||
     Ivan Ivanov (ivan) New member Username: ivan Post Number: 1 Registered: 11-2008 |
Hello everyone, could you please explain if there is a possibility to define an integral BC in FlexPDE. For example, I have a line boundary and I know the integral of a gradient of this variable on this line. I don't know the vlue of a variable in every point but an integral of values of this variable over the whole line. Can I define that? Thanks. | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 1189 Registered: 06-2003 |
You can apply an integral Constraint to a boundary. See "Constraints" in the Help Index and sample problems Samples|Misc|Constraints|Bdry_Constraint.pde Samples|Misc|Constraints|3D_Surf_Constraint.pde The imposition of a boundary constraint may not be sufficient to make the solution unique, as there may be many solutions with the same integral. | ||
| Ivan Ivanov (ivan) New member Username: ivan Post Number: 2 Registered: 11-2008 |
Dear Robert, thank you for your reply. Could you please answer one more question. I also need to make the value of the variable fixed on a line. I mean that the variable can vary in time but it is always the same in every point of a boundary. Can I do that? | ||
| Marek Nelson (mgnelson) Moderator Username: mgnelson Post Number: 89 Registered: 07-2007 |
If you know the time-dependent value function, you can simply state the value boundary condition. e.g. VALUE(u)= 3*t+5 If you do not know the value but wish to calculate it, you can use a GLOBAL VARIABLE. State the function in terms of the global variable and provide equations for the global in the EQUATIONS section. See "GLOBAL VARIABLES" in the Help index and the example "Samples | Misc | Heaterti.pde" |