A numerical model for simulating plasmas, named PLASIMO, is presented. It is capable of simulating multicomponent polyatomic plasmas, in a wide pressure range (10−3 to 1 bar), in local thermal equilibrium (LTE) as well as non-LTE, and with different energy coupling principles. PLASIMO is a fluid model which numerically solves the set of hydrodynamical transport equations. The structure of the model is transparent. It is divided in three main
modules: the main numerical part which forms the heart of the model, the plasma configuration part, and the gas composition part. The strong modularity makes PLASIMO
easy to handle and easy to adjust or expand. The fundamentals of PLASIMO are presented and to demonstrate applications of the model it is applied to a flowing argon cascaded arc plasma, an argon ICP, and a hydrogen plasma in a diverging cascaded arc channel.