Reply To: Residual upset for melting simulation

[flo.schuster]

Hi, 

thanks for the reply.

No, the melt-regime should not absorb radiation anyways, as only a combined thermal conductivity could be determined experimentally, also including radiation absorption. Additionally, it seems suited perfectly to model radiative heat transfer in vacuum.

The melting material is also sought to be described by either a piecewise linear description or a user-defined, named expression to fit experimental data. But this seems to be the problem after conducting some more tests. A constant value, simple sloped function or Boussinesq approach would work but do not reflect reality closely enough. The subsequent fluid movement in the melt regime is only driven by buoyancy forces so an accurate description is vital.

Based on geometry and viscosity, a flow speed between 1e-1 and 1e1 m/s is expected.

What approaches can be used to accurately describe the melting material's density? From room temperature up to 1300K the density should be defined as constant at roughly 1400 kg/m^3 and then at least gradually increase to roughly 2600 kg/m^3 at 1700K. So far I tried using a user-defined expression, namely the logistic function for a smoother transition than a piecewise linear description. 

Are there approaches that ensure higher solver robustness?

Thanks in advance for the help :)