Transient boundary?
 

I am using the transient boundary condition(compressible, transient) to consider the shockwave passing the computational domain.

But I observed the passage of shockwave but after passing the computational domain, the weak pressure region followed. Then vector field becomes unphyscial behavior. As I see, the normal component of vector to the transient boundary set to zero, there are only horizontal velocity. It seems like the wall !!!!

What is the problem in that case?