Francesco,
It could be a problem of ODE stability, error control, nonlinear solver
(cold start), etc.
In addition to what's been recommended, I would suggest trying a
different integrator with better properties: try
-ts_type arkimex -ts_arkimex_type 2e -ts_arkimex_fully_implicit
In case it's a cold-start problem, arkimex methods can provide warmer
guesses: to do that try adding
-ts_arkimex_initial_guess_extrapolate
To take off the error controller, use -ts_adapt_type none
This should take care of the common things.
Emil
On 2/10/16 6:33 PM, Francesco Magaletti wrote:
First of all thank you everybody for the fast replies.
Barry,
I think the solution 1 is a good suggestion but I confess I’m a bit scared of
going deep into the modification of the ODE integrator.
I’m now using TSCN, the classical Crank-Nicolson 2nd order full implicit time
integration. Maybe I can try to implement your solution
together with BEULER, as suggested by Hong.
By the way the solution changes rapidly, but not so fast to justify that small
timestep value. The space variation instead are really fast and this is the
reason why I need so many grid points.
Jed,
I hope you could solve soon the problem with the FAS scheme.
Thank you again
Francesco
