  Stokes drift has been as central to the history of wave theory as it has been
distressingly absent from experiment. Neither wave tanks nor experiments in
open bodies detect this without nearly canceling "eulerian flows." Acoustic
waves have an analogous problem that is particularly problematic in the
vorticity production at the edges of beams. Here we demonstrate that the
explanation for this arises from subtle end-of-packet and wavetrain gradient
effects such as microbreaking events and wave-flow decomposition subtleties
required to conserve mass and momentum and avoid fictitious external forces.
These losses occur at both ends of packets and can produce a significant
nonviscous energy loss for translating and spreading surface wave packets and
wavetrains. In contrast, monochromatic sound wave packets will be shown to
asymmetrically distort to conserve momentum. This provides an interesting
analogy to how such internal forces arise for gradients of electromagnetic
wavetrains in media. Such examples show that the interactions of waves in media
are so system dependent as to be completely nonuniversal. These give further
examples of how boundary effects must be carefully considered for conservation
laws especially when harmonic functions are involved. The induced flows in
establishing surface waves are shown to be time changing and dependent on wave
history and suggest that some classical work based on mass flux and wave
interactions may need to be reconsidered.
