Marina,
From your description, it sounds like you have a diffusion interface (and hence a dependent variable) that is only active on domain A, and another (with a different dependent variable) that is only active on domain B. If this is correct, and if you want the concentration to be continuous across the boundaries between domains A and B, you need to apply a Dirichlet boundary condition (i.e. a "Concentration" boundary condition in the diffusion interfaces) at the boundaries between domains A and B. For the variable in domain A, the concentration at these boundaries should be set to be equal to the variable in domain B, and vice versa.
If I'm not correctly understanding your problem, you could upload a model file or provide a more detailed description of the physics setup for the diffusion variables.
--
Luke Gritter
AltaSim Technologies
From your description, it sounds like you have a diffusion interface (and hence a dependent variable) that is only active on domain A, and another (with a different dependent variable) that is only active on domain B. If this is correct, and if you want the concentration to be continuous across the boundaries between domains A and B, you need to apply a Dirichlet boundary condition (i.e. a "Concentration" boundary condition in the diffusion interfaces) at the boundaries between domains A and B. For the variable in domain A, the concentration at these boundaries should be set to be equal to the variable in domain B, and vice versa.
If I'm not correctly understanding your problem, you could upload a model file or provide a more detailed description of the physics setup for the diffusion variables.
--
Luke Gritter
AltaSim Technologies