UDF regarding melting and solidification of phase change materials for different time periods

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Sumeet
Sumeet Member Posts: 1

Hello, everyone. I am studying the melting and solidification behavior of phase change material (PCM) in the heat pipe for subsequent time cycles. Cold fluid flows in the inner pipe while the PCM is stored in the annulus region of the heat pipe. During the charging process, the flux boundary condition at the outer surface of the heat pipe is applied, while during the discharging process, the convection boundary condition is given at the outer surface of the heat pipe. For this, I have to write the UDF in such a way that when the PCM completely melts during the charging process, the convection boundary condition automatically applies. Once it completely solidifies during the discharging process, the heat flux boundary condition activates again, and similarly, the convection boundary condition activates when PCM completely melts. So, this melting and solidification process continues for different time periods. Can anyone please help?