  We present a hydrodynamical study of the final stages of inspiral in a black
hole-neutron star (NS) binary. We use a Newtonian 3D SPH code, and model the NS
with a stiff (index G=3 and G=2.5) polytropic equation of state and the black
hole as a Newtonian point mass. Our initial conditions correspond to
irrotational binaries in equilibrium (approximating the NS as a compressible
ellipsoid), and we have explored configurations with different initial mass
ratios, 0.2< q=M_ns/M_bh<0.5. The dynamical evolution is followed for ~23ms. We
include gravitational radiation losses in the quadrupole approximation for a
point-mass binary. For G=3, after an initial episode of mass transfer, the NS
is not completely disrupted and a remnant core remains in orbit about the black
hole. For G=2.5 the disruption is more complex, with the NS being totally
disrupted during a second periastron passage. The accretion disc formed around
the black hole contains ~0.2 solar masses. A nearly baryon-free axis is always
present in the system, and only modest beaming of a relativistic fireball that
could give rise to a GRB would be sufficient to avoid baryon contamination.
Around 0.01 solar masses may be dynamically ejected from the system, and could
contribute substantially to the amount of observed galactic r-process material.
We calculate the gravitational radiation waveforms in the quadrupole
approximation. We also present the results of simulations that have used
spherical NSs relaxed in isolation as initial conditions, in order to gauge the
effect of using non-equilibrium initial conditions on the coalescence.
