  Gamma Ray Bursts (GRB) are the extremely energetic transient events, visible
from the most distant parts of the Universe. They are most likely powered by
accretion on the hyper-Eddington rates that proceeds onto a newly born stellar
mass black hole. This central engine gives rise to the most powerful, high
Lorentz factor jets that are responsible for energetic gamma ray emission. We
investigate the accretion flow evolution in GRB central engine, using the 2D
MHD simulations in General Relativity. We compute the structure and evolution
of the extremely hot and dense torus accreting onto the fast spinning black
hole, which launches the magnetized jets. We calculate the chemical structure
of the disk and account for neutrino cooling. Our preliminary runs apply to the
short GRB case (remnant torus accreted after NS-NS or NS-BH merger). We
estimate the neutrino luminosity of such an event for chosen disk and central
BH mass
