what is unresrined expansion of ideal gas? why thereis no colling occures

unresrined epansion means expansion of gas without any external hinderence or ithout any external pressure.  This expansionis irreversible and hence from the work formula w = -p(ext)*(change in vol.) the work done is 0. also there is no heat transfer in this expansion hence the change in internal energy will be zero due to no cooling occurs.