  Within the framework of the quantum molecular dynamics transport model, the
collective flows of clusters and pions in heavy-ion collisions have been
systematically investigated. The clusters are recognized by the Wigner
phase-space density approach at the stage of freeze out in nuclear collisions,
i.e., deuteron, triton, $^{3}$He and $\alpha$. The directed and elliptic flows
of protons and deuterons in the reaction of $^{197}$Au+$^{197}$Au at incident
energy 1.23\emph{A} GeV are nicely consistent with the recent HADES data. The
higher order collective flows, i.e., triangular and quadrangle flows, manifest
the opposite trends with the less amplitude in comparison with the rapidity
distributions of directed and elliptic flows. The flow structure of $^{3}$He
and $\alpha$ is very similar to the proton spectra. The influence of the pion
potential on the pion production is systematically investigated and compared
with the FOPI data via the transverse momentum, longitudinal rapidity and
collective flows in collisions of $^{197}$Au + $^{197}$Au. It is manifested
that the pion yields are slightly suppressed in the domain of mid-rapidity and
high momentum. The antiflow phenomena is reduced by implementing the pion
potential and more consistent with the FOPI data in collisions of
$^{197}$Au+$^{197}$Au at the incident energy 1.5\emph{A} GeV.
