[yt-dev] yt for lagrangian hydro

[Matt Terry]

> Well, so Tom and Jeff let me know that they think this could be
> avoided if ghost zones were written out.  Does your code have the
> ability to write out ghost zones?

None of our methods are better than 2nd order in space, so stencils
only need neighboring cells.  On disk, there is no duplicate data, so
we'd need to construct ghost zones along block boundaries ourselves.
as for domain boundary ghost zones, i don't think the ghost zones are
saved to disk.  i'm not sure if boundary conditions are saved so that
we can reconstruct them.  adding information to the binary file
shouldn't be a big deal either way.

> That would alleviate a substantial
> amount of the trickiness of spatial locality, as we could just read
> those in and use them for any finite difference stencil fields.  (And
> if not, we can just ignore it, and raise a "Don't know how to generate
> ghost zones" error.)  So I think we can ignore spatial locality for
> the moment as a problem.
>
>>
>> right now, all my visualization/analysis is slices and profiles, so
>> not having volume rendering isn't a loss.  having it would be a very
>> persuasive feature, though.  on that topic, volume rendering will take
>> a bit of work, since we'll have to rewrite the ray casting routines to
>> deal with an irregular structured mesh.  i'll say from experience,
>> that ray trace through Lagrangian meshes is unpleasant.  its all
>> corner cases.
>
> Okay, let's hold off on this for now.  Maybe once we've seen the data
> we can test some ideas, but let's explore this later.

there are scripts floating around llnl for doing the ray trace.  so i
don't think i'd need to write this from the ground up.  but i agree,
baby steps.

>>
>> assuming we drop volume rendering, this sounds like a few days work to
>> get all the pipes connected to the right places.  it also sounds like
>> i should wait for v3 to finish baking before diving in.  this is all
>> well and good, because it will be a month or so before i really have
>> the bandwidth to work on this in earnest.
>
> Sounds great.  Let's plan on revisiting this -- but I definitely think
> it's feasible.  And fun.

is yt3 is a state to begin poking around?