  In this paper, the second in a series, we document the algorithms and solvers
for compressible nonrelativistic hydrodynamics implemented in GenASiS (General
Astrophysical Simulation System)---a new code being developed initially and
primarily, though by no means exclusively, for the simulation of core-collapse
supernovae. In the Mathematics division of GenASiS we introduce Solvers, which
includes finite-volume updates for generic hyperbolic BalanceEquations and
ordinary differential equation integration Steps. We also introduce the Physics
division of GenASiS; this extends the Manifolds division of Mathematics into
physical Spaces, defines StressEnergies, and combines these into Universes. We
benchmark the hydrodynamics capabilities of GenASiS against many standard test
problems; the results illustrate the basic competence of our implementation,
demonstrate the manifest superiority of the HLLC over the HLL Riemann solver in
a number of interesting cases, and provide preliminary indications of the
code's ability to scale and to function with cell-by-cell fixed-mesh
refinement.
