Urea system in automotive and its behaviour in cold weather: development of a calculation method with CFD Nowadays is very important in engineering fields dealing with transport, as automotive, but also aerospace engineering, to control and to reduce polluting factors. In this work an urea based system for automotive purposes is analysed from a thermofluidodynamic point of view. This kind of solution is adopted in diesel engines in order to decrease the nytrogen oxides emissions and to comply new EU requirements for combustion cars. The problem of icing or deicing and its simulation in the CFD software STAR CCM+ in order to create a method to run the cases related to deicing of the urea system is considered in this work.