Properties of Quark-Gluon-Plasma from collective flow

Heavy ion collisions at the Relativistic Heavy Ion Collided (RHIC, BNL) and at the Large Hadron Collider (LHC, CERN) have revealed a new state of matter, the so-called Quark-Gluon-Plasma (QGP). In this QCD plasma, the quarks and gluons confined within the hadrons get deconfined over the nuclear volume analogous to that in a QED plasma comprising of electrons and photons. Precise estimation of the properties of this smallest and yet the hottest droplet gives us a complete understanding of how particles are produced via strong interaction. In this talk, I will focus on one of the most important probes of QGP - the collective flow of particles (hadrons) produced in a complex dynamics that involves multiscale QCD processes. Standard methods and new approaches to explore the collective flow of plasma will be presented. The state-of-the-art models: Transport and Hydrodynamic, used to study the QGP evolution will be reviewed. Finally, from the synergy between these approaches, models and experimental data, I will discuss what we presently know about the thermodynamic and transport properties of QGP and some interesting open questions.