Hi Junru,
Thank you for posting your questions to the forum, which I’ve posted some initial responses to below.
I’d like to use the compositing model to combine the two models (viscoplastic model and melt model) to change the density.
While you can use a compositing approach, I suggest using the reactive fluid transport material model (see material model documentation).
This material model directly composite a base model (such as visco plastic), with the functionality for handling fluid transport and reactions.
This material model also uses a new reaction module design, which will allow users to more easily develop and implement new reaction modules in a modular fashion.
But when I have more than one composition (like crust, mantle, etc.), how should I set the density for each composition? Which model should I choose for the Density option in the Compositing model (viscoplastic or melt model) to make the depletion-related density change considered?
I think the best approach would be to do this in a new reaction model, where you use the name of the field and field type to determine how the densities (and other properties change).
I’ve noticed previous discussions that suggest modifying the code to achieve this. I would like to seek some advice on how to implement this functionality.
Can you specify what additional information is needed beyond the advice provided in the linked discussions?
I think the first step would be to write out the equations and workflows for a simple analytical case, such as the reactions and change in material properties as P-T conditions change at a single point.
This benchmark then provides a reference case that you can try to reproduce in ASPECT with the new functionality.
Cheers,
John