n-body simulation

cosmoboy

Hi,
Could some body please explain me how to identfy the size of simulation box in cosmological n-body simulation with the physical scales in the universe. For example if I am using 128 grid points along one direction in a Particle Mesh code and total number of particles are 128*128*1228. Now there are two options, first is; we equate the density of particles in simulation box and compare it with the actual density of galaxies in the universe (for simulating galaxy clustering)
and second, we find the size of a spherical region at z=0, in which density fluctuatios are of the order of unity and identify it with
8 Mpc (Using COBE normalization, CDM spectrum).
Let me know if anyone has the answer

hellfire

I cannot answer your question, but I a short time ago I had also some questions related N-body simulations (http://www.physicsforums.com/showthread.php?t=43890). I did search some information about the subject and I found this paper:

Cosmological N-Body simulation: Techniques, Scope and Status
http://arxiv.org/abs/astro-ph/0411043

May be it helps (although I had no time to read it till now and I do not know whether there is an answer to your question there).

cosmoboy

dear hellfire ,
thanks