Inside square steel container filled with water (5mm thick), a piezo
transducer, immersed in the middle of the tank, transmits at 1MHz.
This generates plane waves propagating outside.

What’s happen to an acoustic PLANE WAVES propagating in the fluid
when
hit the steel?

Can the waveforms generated (i.e. shear waves, lamb waves) inside the
steel be similar (the same kind, not the same energy) to small
particles striking inside the inner wall of the tank?

I would like to know is that I can propagate the same sort of waves
after the boundary.
Are the plane waves generated by the transducer again planewaves
after
the border?

Is the particle a point source emitting in all directions (after the
border) while the transducer generate only plane waves?
Thanks
Nick

Def: Point source
An ideal point source can be considered as a pulsating sphere that is
infinitesimally small in size. The sphere is omni-directional, i.e.
sound energy is emitted equally to all directions. Due to geometrical
attenuation, the sound pressure level is reduced by 6 dB for each
doubling of distance from the source.
Def: Plane wave source
An ideal plane wave source consists of a pulsating rigid surface that
is infinitesimally thin and has infinite length and width. The
surface
radiates sound energy equally to its front and back directions. A
plane wave source produces a plane wave, which (in the ideal case)
does not exhibit geometric attenuation with increasing distance from
the source