# Acoustic Waveguide and boundary conditions “free boundary”

I have a question about boundary conditions. I need to solve the wave equation with a rigid boundary at y=0 and a free boundary at y=h. I know this means that we have zero normal component of velocity at y=0. However, what does free boundary imply? Is it that the pressure is zero at y=h?

• The pressure can be taken as constant and there is also a kinematic condition as derived here. – RRL Jan 28 at 14:45