Ls-dyna fluid structure interaction

Hi all

I want to use LSDYNA to model a detonation process involving fluid structure interaction. A solid structure is embeded in a viscous fluid media. Due to symmetry of the model, a quarter of the model is analysed. So my question is 

1) How to model the symmetric condition in the Euler element domain? since the Euler meshes is fixed, it seems applying constraint on the nodes in the symmetric plane is meaningless.

2) How to model the infinite boudanry condition in the free surface of the fluid Euler domain?

Thanks

 Wei