Ray asymptotics of a clamped elastic waveguide mode
= Ray asymptotics of a clamped elastic waveguide mode
A <shear-horizontal wave> mode has $\omega_n(k)=c_s\sqrt{k^2+(n\pi/h)^2}$. At $x=Vt$ with $0<|V|<c_s$, a nondegenerate stationary Fourier phase gives generic $t^{-1/2}$ decay. Faster rays have no <stationary point>; compactly supported data give eventual zero by <finite propagation speed>.