Hi. I want simulating a flow of fluid(liquid) which become vapor if the pressure of fluid at a point decrease under the vapor of pressure at this temperature. How can i this? is there a procedure in fluent which vaporate the fluid when the pressure is the vapor pressure? Or i must define two faces (liquid and vapor of this liguid)? On second case how i activate the procedure of vaporization when the pressure is vapor pressure of liquid?

If this is a cavitation problem, then Fluent has a cavitation model to predict phase change due to pressure drop

Yes. Is the cavitation problem. And how can i use this model? Can you help me find this procedure?

you can turn on the cavitation model in FLUENT if you are using the mixture model for multiphase flow, which is an Eulerian-Eulerian multiphase model. you can find all the information you need in FLUENT's user guide manual. precisely, in the chapter of general multiphase models in the section of (description of mass transfer)