Here are some Chladni figures of
of the Barycentric refinement G3 of the
triangle K3. This graph has 121 vertices. The level surfaces are in the refinement G4
shown here. We want to understand the spectral gaps, the discontinuities of the spectral functions F.
Like the gap occurring at x=1/2, which corresponds to the change from eigenvalue number 60 to
number 61.
See the preprint "The graph spectrum of barycentric refinements"
for the math and mini blog,
Same pictures for G3,
a polyhedron or
or a square.