A cylinder oscillates vertically at in a tank stratified with

PHYSICS · Multi-part · Fermi University Physics · Oscillations, Waves & Acoustics · Fluids & Continuum Physics · Waves, acoustics and compressible flow

Signal Speeds in Fluids, Ch Internal gravity waves in a stratified fluid

Problem

A cylinder oscillates vertically at ω=0.80 rad s−1\omega = 0.80\,\mathrm{rad\,s^{-1}} in a tank stratified with N=1.00 rad s−1N = 1.00\,\mathrm{rad\,s^{-1}}, radiating a St Andrew's cross. A schlieren film of the lower-right beam shows the crests moving steadily up and to the right, across the beam, as time passes. ((a)) Find the angle this beam makes with the vertical. ((b)) State, with a reason drawn from the internal wave group velocity, the direction in which energy is being carried along this beam, and reconcile it with the crests visibly moving up and to the right.

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