How to implement subroutine to modify domain type?

Chin

Dear all,

Let me describe my intention:

1) I have 3 domains set up for a Transient simulation.

2) The first 10 seconds, the domains are Fluid-Solid-Fluid, so there will be no flow across since the Solid domain is blocking the channel.

3) In the next 10 seconds, the domains become Fluid-Fluid-Fluid, so the middle domain acts as an opening valve that enables flow through the domains.

4) In the beginning, the domains are connected using Fluid-Solid, and Solid-Fluid interfaces; but the interfaces will change into Fluid-Fluid connection after 10 seconds, and vice versa.

Procedures 2~4 shall be repeated multiple times.

My question is:

=> How to implement subroutine to modify domain and interface types while the solver is running to solve a transient problem?

Thank you, and hope to hear from you all soon.

Cheers!