Reply To: Transmit boundary – reflection / perturbation of pressure waves

[Chris Quan]

For multi-material Euler solver, usually Flow Out boundary condition is used. Can you try the Flow Out BC to see if you still observe the large oscillations of pressure near the boundary? Make sure the correct material is selected for flow out or set it to ALL Equal. 

For impact simulations, it is OK to observe a rarefaction wave after the initial compressive wave.

From the profile picture included in your description, I estimated that the sound speed of the material exceeds 10000 m/s, which seems large to me. Can you carefully check the material properties in your model to make sure they are accurate?