[Kelvin Wedge] Relations among Rays, Group Velocity, Phase Velocity, and the Wave Number Vector in Water Waves
In dispersive water waves (e.g., surface gravity waves on deep or
shallow water), several concepts describe how waves travel, how energy
moves, and how the wave patterns evolve. Below is an overview of
wave fronts, wave crests, the
wave number vector \(\mathbf{k}\), phase
velocity \(\mathbf{c}_p\),
group velocity \(\mathbf{c}_g\), and rays,
along with how their directions compare.