Miguel

LegoExcision was never working satisfactorily, and is not supported any more. The problem is (likely) that the characteristic velocities across the Lego boundaries may not all have the same sign (outflowing). I thus recommend to use a smooth excision surface, as Jonah suggests below.

Using excision for the hydrodynamic quantities, if done inside the black hole, is also possible, but that is usually combined with punctures for the geometry.

-erik

On Mon, Mar 27, 2017 at 10:59 AM, Jonah Miller <jonah.maxwell.miller@gmail.com> wrote:

Hi Miguel,

I'm not sure about excising dynamically during evolution--maybe someone else has insight there. However, excision is definitely possible. I have been using the sixpatches Llama thorn to perform excision for a single black hole. I attach a parameter file to excise a Kerr-Schild black hole that I based my simulations on.

Best,

Jonah

On 2017-03-27 05:01 AM, Miguel Zilhão wrote:

hi all,

i was wondering whether one could straightforwardly use the ET to perform black hole
evolutions using excision instead of punctures.

specifically, i had in mind a collapsing configuration where i'd like to excise the inner
domain once a black hole horizon is formed... is this possible?
i had a look around and noticed the LegoExcision thorn, but i'm not sure whether it's
actively maintained, nor whether it can interface with McLachlan...

thanks,
Miguel
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Erik Schnetter <schnetter@cct.lsu.edu>
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