Re: [ff3d-users] trivial solution

[Mourad Ismail]

Hi,
I am not sure to have understood, but it seems obvious that you have the 
trivial solution.  Your problem doesn't have a unique solution!
The initial guess is 0 which is  a solution of the problem.
A solution may be to add a radiation condition
Don't hesitate to tell me if I am mistaken.

Best regards,
Mourad

On Monday 07 March 2005 20:38, Neil Christensen wrote:
> Hi,
>     I am trying solve the pde:
>
>     div(grad(phi))  + phi = 0
>
> with the boundary condition
>
>     phi = 0 on <1,0,0>.
>
> As you know the analytic solution to this is
>
>     phi = sum_i  a_i cos(k_i . r) + b_i sin(k_i . r)
>
> where a_i, b_i and k_i are chosen such that the boundary condition is
> satisfied.  In my first attempt, the boundary I used was a square.  The
> problem is that when I run ff3d on it, I only get the trivial solution
> phi = 0.  How can I get other solutions?
>     Thank you,
> Neil
>
>
> _______________________________________________
> ff3d-users mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/ff3d-users

-- 
| Mourad Ismail
| Projet ONDES, INRIA-Rocquencourt
| Domaine de Voluceau-Rocquencourt
| B.P. 105, 78153 Le Chesnay Cedex
| Tél. 01 39 63 55 71  Fax 01 39 63 58 84
| http://www-rocq.inria.fr/~ismail

pgp2B6RYtSDd_.pgp
Description: PGP signature