Comoving integration

From: Evgeny Kurbatov <>
Date: Fri, 12 May 2006 13:29:44 +0400


Please help me to shed light on four questions:
1. The drift factor looks as if the internal velocity variables would be
        a^2 \dot{x} ,
where `x' is the comoving coordinates and `a' is the scale factor. But
procedures `init' and `fill_write_buffer' tell us that internal velocity is
        a^{3/2} \dot{x}
(I mean that the `\dot{x}' stores in a snapshots).
2. Why the gravkick factor is
        \int da / (a^2 H) ?
3. Why the hydrokick factor differs from the gravkick factor?
4. How in the GADGET-2 the cooling due to cosmological expansion
realizes? Looking into the code I didn't find corresponding term in the
DtEntropy calculation.

Received on 2006-05-12 12:30:27

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