1D valve simulation (gas dynamics)
 

Hi!
Tell me how to put the boundary conditions at the valve.
I do so:
1. Find fluxes ​​between the end of one pipe and the beginning of another (F1)
2. Find the reflected flux (Fref)
3. Convert the flow as follows: Fres = F1*kv + Fres*(1-kv)
kv - [0,1] transmission factor

But I have obtained unphysical jumps at the ends of the pipes.
How to set boundary conditions?