moving mesh grid interface

Dieter

hello,

I have a train who enters a tunnel. There are 2 grids and one of them moves. Between the 2 grids is there are 2 interfaces. With me this are 2 lines (2D) who overlap. But if i want to make a grid interface it creates 2 walls automatically. I don't want the walls because my flow has to go through the interfaces. In the user guide 33.3.19 there is stated (at the Boundary Zone 1 and Boundary Zone 2 point) that "If the two interface zones overlap completely ..., no wall zones will appear." But with me they do. What is wrong?

Thanks for the help

greetings

Dieter