  In this paper, we consider an effective quintessence scalar field with a
power-law potential interacting with a $P_{b}=\xi q\rho_{b}$ barotropic fluid
as a first model, where $q$ is a deceleration parameter. For the second model
we assume viscous polytropic gas interacting with the scalar field. We
investigate problem numerically and analyze behavior of different cosmological
parameter concerning to components and behavior of Universe. We also compare
our results with observational data to fix parameters of the models. We find
some instabilities in the first model which may disappear in the second model
for the appropriate parameters. Therefore, we can propose interacting
quintessence dark energy with viscous polytropic gas as a successful model to
describe Universe.
