I am trying to model gas flowing in a metal pipe. The pipe has heat source and is insulated. I used hex-dominant parametric multi-region mesh. Defined boundary conditions for inlet, outlet and power applied to the outside of pipe. I tried to define or not define interface for pipe-insulation. The simulation crashes both times, the error is "Inconsistent definition of interface: this happens when one side of an interface is assigned to a boundary condition. You can avoid this by removing interface faces from boundary conditions." It seems from the log that the problem is the insulation, once it starts to solve that volume, it crashes. How do you set it up correctly?