Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bragg's reflection for walking droplets in 1D crystals   A walking droplet possesses fascinating properties due to its peculiar
wave/particle interaction. The self-propelling motion of such a droplet is
driven by the Faraday instability triggered around the droplet at each impact.
We studied in this article how such a droplet behaves in an annular cavity
where a periodic pattern is placed underneath the liquid-air interface,
altering the Faraday instability. We show that, while the annulus ensures a
circular motion of the droplet, the periodic pattern affects the global droplet
motion. Similarly to electromagnetic waves in photonic crystals, the average
droplet speed nearly vanishes when the pattern has a characteristic length
close to half the Faraday wavelength. This effect opens ways to design guides,
reflectors, lattices and metamaterials for such macroscopic particles.

16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
37
The categories of this paper are: supr-con
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
19
The categories of this paper are: eess
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc