[Lino96]

Hi. I'm simulating a rotating heat pipe with condensation (Boundary condition heat flux = -10 ^ 6). Initially, I have steam with a fill ratio of 8% (water). I am working with the VOF multiphase model. My big problem is that both with the UDF that I am attaching here, and with the default model of fluent I have an uncontrolled temperature increase after a few hundredths of a second that has no way to exist. Besides, I have the minimum temperature that drops below zero inexplicably. Anyone can help me? Thank you.

In addition, some other informations: I am using an explicit VOF model with a constant surface tension of 0.072. A rotation of 2000rpm with a heat flux imposed on the condenser of -10 ^ 6. Obviously it is a multiphase model with water and steam, neglecting the air. As said I tried to use different Udfs and also the default Fluent model with no results. I tried to change the relaxation factors, considered the vapor as an ideal gas, set to second order momentum, energy etc ... all to no avail. Actually my goal is to consider evaporation afterwards too, but here another problem arises that I cannot simulate situations.

UDF solo condensazione.c

Nuova UDf contorno temperatura.jpg

Nuova Udf Temp si alza.jpg

T_min.jpg