Being able to alternate subdomain ID values according to variable values would be useful in simulating diverse physical phenomena, e.g., mechanical, thermal, chemical, etc., when phase transition happens.
Design
Create a UserObject based on the existing `ElementSubdomainModifier, which would be able to modify element subdomain IDs based on a coupled variable value.
Motivation
Being able to alternate subdomain ID values according to variable values would be useful in simulating diverse physical phenomena, e.g., mechanical, thermal, chemical, etc., when phase transition happens.
Design
Create a UserObject based on the existing `ElementSubdomainModifier, which would be able to modify element subdomain IDs based on a coupled variable value.
Impact
Allow subdomains to change during simulation.