Astronomical bounds on a cosmological model allowing a general
  interaction in the dark sector
  Non-gravitational interaction between two barotropic dark fluids, namely the
pressureless dust and the dark energy in a spatially flat
Friedmann-Lema\^{i}tre-Robertson-Walker model has been discussed. It is shown
that for the interactions which are linear in terms the energy densities of the
dark components and their first order derivatives, the net energy density is
governed by a second order differential equation with constant coefficients.
Taking a generalized interaction, which includes a number of already known
interactions as special cases, the dynamics of the universe is described for
three types of the dark energy equation of state, namely that of interacting
quintessence, interacting vacuum energy density and interacting phantom. The
models have been constrained using the standard cosmological probes, Supernovae
type Ia data from joint light curve analysis and the observational Hubble
parameter data. Two geometric tests, the cosmographic studies and the $Om$
diagnostic have been invoked so as to ascertain the behaviour of the present
model vis-a-vis the $\Lambda$-cold dark matter model. We further discussed the
interacting scenarios taking into account the thermodynamic considerations.
