  By means of HARM\_COOL\_EOS, which is our code for conservative relativistic
magnetohydrodynamics, we developed a new scheme for the simulation of a system
formed after compact binary merger. Our code works with a tabulated equation of
state of dense matter, accounts for the neutrino leakage, and follows the mass
outflows via the tracer particle method. We discuss the numerical scheme, and
present the recovery method included in our code. We also show results of a
numerical simulation, addressed to the post-merger system after the coalescence
of binary neutron stars, or a neutron star with a stellar mass black hole. The
plasma is very neutron-rich, so the r-process nucleosynthesis in the ejected
material may lead to unstable heavy isotopes creation. They are responsible for
an electromagnetic signal, observed as a kilonova. In addition, the magnetized,
neutrino-driven wind can act as a collimating mechanism for the relativistic
jet.
