Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Globally aligned states and hydrodynamic traffic jams in confined active
  suspensions   Strongly confined active liquids are subject to unique hydrodynamic
interactions due to momentum screening and lubricated friction by the confining
walls. Using numerical simulations, we demonstrate that 2D dilute suspensions
of fore-aft asymmetric polar swimmers in a Hele-Shaw geometry can exhibit a
rich variety of novel phase behaviors depending on particle shape, including:
coherent polarized density waves with global alignment, stationary asters,
persistent counter-rotating vortices, density shocks and rarefaction waves. We
also explain these phenomena using a linear stability analysis and a nonlinear
traffic flow model, both derived from a mean-field kinetic theory.

19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
1
The categories of this paper are: cs
18
The categories of this paper are: econ
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
2
The categories of this paper are: math
20
The categories of this paper are: acc-phys
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg