boundary conditions for explosion in a tube
 

Hello!

I am simulating an explosion inside a tube. I can not figure out how to set the wall boundary conditions for the pressure p in the folder 0/p so that the wall pressure is calculated. Now I only can start simulation, when I set the wall boundaries for the walls to "fixedValue" and set that value to 1 bar. When I set them to "calculated", the simulation crashes in the first timestep. What am I doing wrong there?

The boundary condition for pressure for walls should be zeroGradient.
rgds
Bjorn