  We analytically study how the behaviour of accretion flows changes when the
flow model is varied. We study the transonic properties of the conical flow, a
flow of constant height and a flow in vertical equilibrium and show that all
these models are basically identical provided the polytropic constant is
suitably changed from one model to another. We show that this behaviour is
extendible even when standing shocks are produced in the flow. The parameter
space where shocks are produced remain roughly identical in all these models
when the same transformation among the polytropic indices is used. We present
applications of these findings.
