[petsc-users] TS_SSP implementation for co-dependent variables

[Jed Brown]

Is it a problem with the spatial discretization or with the time
discretization that you've been using thus far?  (This sort of problem
can occur for either reason.)

Note that an SSP method is merely "preserving" -- the spatial
discretization needs to be strongly stable for an SSP method to preserve
it.  It sounds like yours is not, so maybe there is no particular
benefit to using SSP over any other method (but likely tighter time step
restriction).

Manuel Valera <mvalera-w at sdsu.edu> writes:

> To correct for the deformation of the sigma coordinate grid... without this
> correction the velocity become unphysical in the zones of high slope of the
> grid. This is very specific of our model and probably will be solved by
> updating the equations transformation, but that's not nearly close to
> happening right now.
>
> On Wed, Oct 9, 2019 at 3:47 PM Jed Brown <jed at jedbrown.org> wrote:
>
>> Manuel Valera <mvalera-w at sdsu.edu> writes:
>>
>> > Thanks,
>> >
>> > My time integration schemes are all explicit, sorry if this a very
>> atypical
>> > setup. This is similar to the barotropic splitting but not exactly, we
>> > don't have free surface in the model, this is only to correct for sigma
>> > coordinates deformations in the velocity field.
>> >
>> > From how i see it this could be solved by obtaining the intermediate
>> stages
>> > and then updating them accordingly, is this not possible to do ?
>>
>> Why are you splitting if all components are explicit and not subcycled?
>>