[Carpet] buffer zones

[Ian Hawke]

On Fri, 2006-05-19 at 15:56 +0200, Frank Loeffler wrote:

> maybe a dump question: apart from performance loss, does it hurt so set 
> too many buffer zones?

If using internal buffer zones then you nullify the effect of the mesh
refinement (as interpolating from the coarse grid loses you the
additional accuracy that the fine grid should give you). With _really_
too many buffer zones you're just doing an expensive unigrid run with a
weird dissipation algorithm!

If using external buffer zones then there is no problem (as long as the
buffers of the first refined grid are contained inside the physical
domain of the coarsest grid, otherwise it doesn't make sense).

Ian