there should be no problem when you first solve the Curvilinear Coordinates (stationary) to get your coordinate system and then use this in a time dependent study for heat transfer, for example.

A time changing coordinate system is not possible, as far as I know. If you are interested in something like this I recommend to discuss this with our support team in more detail via https://www.comsol.com/support

Best Regards,

Nancy

Thanks for å detailed discussion, I have one issue though:

I need to consider aniso-tropic thermal expansion, but I have no coordinate frame selection list to choose from in the thermal expansion sub-node, in contrary to your example of the thermal conduction k.

So what are the correct equations & variable names to use in this case? V5.0

Sincerely

Ivar