zoom simulation

From: Jun-Hwan Choi <jhchoi_at_physics.unlv.edu>
Date: Wed, 15 Sep 2010 14:35:34 -0700

Dear Gadget users,

I am working on "zoom simulations" with multi-mass particle initial
condition, and I face on a few questions.

It looks like that there are two ways to implement zoom simulations.
One is that different mass of dark matter can be assigned to different
particle types and each types has different softening length.
Another is turning on PLACEHIGHRESREGION flag in Makefile.
Is it true that there are two ways? (If so what is the difference?)
In addition, if I use a latter approach, I can generate more than two
different masses for dark matter particles.
In this case, how do I choose softening length?
Do I choose one from high resolution particles or use ADAPTIVE_GRAVSOFT
It is known that if I use ADAPTIVE_GRAVSOFT for different mass SPH, it may
seriously violate the energy conservation.

I also consider to include SPH particles in zoom simulations.
Is there any restrictions when implementing SPH simulation with more than
two different masses of SPH particle?
In gadget, SPH can be only one type (type=0).
It means, I again face on the softening problem I mentioned above.
Therefore, I think to place SPH particle only in high resolution region.
In this case what happen for the SPH particle at the boundary of this
region? (Does they show an artificial expansion?)
How can I get around these numerical problem?

Thank you in advance,

Jun-Hwan Choi, Ph.D.
Dept. of Physics & Astronomy, UNLV
Tel: 702-895-5840 Fax: 702-895-0804
Received on 2010-09-15 23:35:39

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