| Author | Message | ||
     neeraj (neeraj) New member Username: neeraj Post Number: 1 Registered: 08-2006 |
I am a new user of FlexPDE. I need to specify boundary conditions for my 3D PDE along a surface of a sphere but in cartesian coordinates. Any suggestions ? | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 678 Registered: 06-2003 |
If you model the problem in 3D, FlexPDE will default to cartesian coordinates, so I don't understand the question. If you model it in 2D cylindrical coordinates, you can write transformation expressions to convert coordinates, so I still don't understand the question. | ||
| neeraj (neeraj) New member Username: neeraj Post Number: 2 Registered: 08-2006 |
Okie, my equation is in cartesian coordinates (the default option.) But, I do not know how to specify boundary conditions that are applicable for a sphere. In other words, I do not know how to "walk" along a spherical surface. | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 679 Registered: 06-2003 |
Boundary conditions are specified on surfaces. On the top surface of a sphere, for example, you could write Natural(u)=3*x or Natural(u)=sqrt(x^2+y^2) to specify a coordinate-dependent surface flux. Similarly, you could write Value(u) conditions as functions of coordinate. In either case, the "x" and "y" coordinates mean the coordinates of the point on the surface for which FlexPDE is computing the flux or value. |