Constructing GravitatingMassField from N-body Particles with AMR

[Bodo Schwabe]

Dear all,

for the last months I have been working with the enzo code, especially with the gravitational routines. I am a bit confused about how the GravitatingMassField is constructed from N-body particles with AMR. Specifically:

Assuming two AMR levels it seems that topgrid particles overlapping with the finer level are not interpolated onto the active region of the GravitatingMassField of the finer level. This results in smaller GravitatingMassField values in the active region of the finer levels at the boundary between two levels. Additionally, since ghost cells on the finer level are first filled by interpolating the GravitatingMassField from the topgrid (which was constructed using also particles from the finer level) and then particles from the finer level are added on top, particles from the finer level seem to contribute twice within the ghost zones of the finer level.

Did I understand the routines correctly?

I am happy to answer any questions or concerns you might have. Thank you in advance for any constructive feedback.

Cheers,

Bodo

[Bodo Schwabe]

I just read that within the Nyx code, this problem is solved via ghost particles. Can anybody tell me how enzo solves the above problem? Thank in advance.