Boundary-forced internal gravity wave
= Boundary-forced internal gravity wave
A moving boundary excites an <internal gravity wave> through its <kinematic boundary condition>. For <wavenumber> $k$ and <angular frequency> $\omega$, the vertical <velocity field> satisfies $W''+k^2(N^2/\omega^2-1)W=0$. The <radiation condition> selects outward <group velocity>; when $\omega>N$, the bounded response is an <evanescent wave>.