Hello, I'm currently researching the phase change of water as heat is applied to a surface. My work is comparable to the wallboiling tutorial (\multiphase\reactingTwoPhaseEulerFoam\RAS\wallBoiling). I understood we had to create separate thermophysical properties for water and steam, and that the phasepropeties file was used to describe the phase change, while Tsat in the phasepropeties file denoted the temperature at which the phase change occurred?

I have two doubts

1)Why is the velocity of steam defined in the same way as the velocity of liquid at the inlet? If I'm not mistaken, water enters at the inlet and is converted to steam once the temperature hits the saturation. This means that steam only emerges in the middle, where a significant temperature is reached, so why does the velocity have to be defined at the inlet?

2)Is it necessary to use 'mapped' patch at the inlet if the velocity has to be defined for both steam and water?