We present a 3d code for the dynamical evolution of a multi-phase interstellar medium ( ISM ) coupled to stars via star formation ( SF ) and feedback processes .
The multi-phase ISM consists of clouds ( sticky particles ) and diffuse gas ( SPH ) : exchange of matter , energy and momentum is achieved by drag ( due to ram pressure ) and condensation or evaporation processes .
The cycle of matter is completed by SF and feedback by SNe and PNe .
A SF scheme based on a variable SF efficiency as proposed by \inlinecite EE97 is presented .
For a Milky Way type galaxy we get a SF rate of \sim 1 { M } _ { \odot } { yr } ^ { -1 } with an average SF efficiency of \sim 5 % .