Why a Shout Above Water Never Reaches Below — Acoustics Across a Diffuse Interface
·6 min read
Near an air–water impedance ratio of 3600, about 99.9% of the sound reflects. The 13.4 degree critical angle is checked in a 1D tube.
How to Make an Outflow Stop Reflecting Sound — Navier–Stokes Characteristic Boundary Conditions
·6 min read
A six-hour LES drifted 0.3 bar because the outlet reflected sound. NSCBC sets the incoming wave with σ near 0.25 so acoustics leave and the mean holds.