What is best method to initialize the solution for phase change materials
Answers
If you want to model a PCM with an air phase on top, you've correctly chosen solidification and melting model and VOF model. For simplicity, the air phase is often neglected and only PCM without volume expansion is simulated. If you use VOF, you have to initialize a solution with the two different materials, e.g. "pcm" and "air", which you have to specify in the VOF settings. The interface is then tracked by the VOF model. The initialization needs 3 steps: 1.) Initialize the first phase, e.g. "pcm" with "pcm volume fraction" 0, i.e. you have only "air" in your domain. 2.) Mark a region, where you want to have pcm: Chose adapt/region from the file menu, input coordinates and then click "mark". 3.) In solution initialization click on "patch", chose phase "pcm", variable "volume fraction", value 1, the marked region in "registers to patch" and then click "patch". Now, check your vof phase contours. If everything is fine, you're ready to start your simulation. Beware that you will need a pressure inlet/outlet or compressible air phase to allow volume expansion. Another to take special care of is material properties of the PCM over phase change, especially density.