Hi Erik,

When you say most people, what do you mean?  Is there an implementation of SPH in a true dynamical spacetime? I know there are a few under the assumption of conformal flatness, but I am not aware of anyone with SPH in dynamical spacetime.

Related to this, is there a reference I can look at which write out the hydro equations in detail.  It is not immediately obvious to me that Rosswog's paper writes it as a hydrodynamic equation on the coordinate manifold with lapse and shift.

Cheers,
Phil

On 9/26/17 6:38 PM, Erik Schnetter wrote:
Phil

Most people let SPH particles move on the background ("coordinate") manifold, with equations of motion similar to those for the hydrodynamics field equations, i.e. taking lapse and shift into account. This is a straightforward approach, as e.g. the shape of a particle remains fixed in coordinate shape. The simplicity of this approach is very attractive.

-erik


On Tue, Sep 26, 2017 at 3:29 AM, Philip Chang <chang65@uwm.edu> wrote:
Dear developers,

I saw that there was a discussion back in 2015 in regard to SPH in the
Einstein toolkit.  Have any progress been made in this regard?  I am
especially interested in how the sph particles move (and what it means
to move) in a 3+1 split.

Cheers,

Phil Chang

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Erik Schnetter <schnetter@cct.lsu.edu>
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