  2-TIPS (Two Temperature induced phase separation) refers to the phase
separation phenomenon observed in mixtures of active and passive particles
which are modelled using scalar activity. The active particles are connected to
a thermostat at high temperature while the passive particles are connected to
the thermostat at low temperature and the relative temperature difference
between "hot" and "cold" particles is taken as the measure of the activity of
the non-equilibrium system. The study of such binary mixtures of hot and cold
particles under various kinds of confinement is an important problem in many
physical and biological processes. The nature and extent of phase separation
are heavily influenced by the geometry of confinement, activity, and density of
the non-equilibrium binary mixture. Investigating such 3D binary mixtures
confined by parallel walls, we observe that, the active and passive particles
phase separate, but the extent of phase separation is reduced compared to bulk
phase separation at high densities and enhanced at low densities. However, when
the binary mixture of active and passive particles is confined inside a
spherical cavity, the phase separation is radial for small radii of the
confining sphere and the extent of phase separation is higher compared to their
bulk counterparts. Confinement leads to interesting properties in the
passive(cold) region like enhanced layering and high compression in the
direction parallel to the confining wall. In 2D, both the bulk and confined
systems of the binary mixture show a significant decrement in the extent of
phase separation at higher densities. This observation is attributed to the
trapping of active particles inside the passive cluster, which increases with
density. similar phase co-existence.
