Mass Ratio q1.0: Equally-spaced Particles

To construct a corotating binary configuration for stars of unequal mass, but with equally-spaced SPH particles in both stars, you can use the ``setup2qs'' subroutine, which is called by setting the three letter code in sph.init to ``2qs''. The code lays down each star in an analogous manner to the equally-spaced single star routines, and the same instructions about the relaxation timescale and shutoff time apply. The mass ratio is determined by the parameter ${\tt QDAR}=M_2/M_1$.

Note that the parameter ``N'' used to initialize the run refers to the approximate number of particles in the primary star, which we typically assume to be the larger star, although no attempt is made to enforce this in the code. The number of particles in the secondary is given approximately by the ratio of the volumes of the two stars, since the code currently using the same grid spacing for BOTH stars. As always make sure the parameter ``NMAX'' in the spha.h header file is as large or larger than the total number of particles needed! There is nothing stopping you from changing the grid spacing of the second star, should you wish, and we are unaware of any negative effects this could cause.