Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Confinement enhances the diversity of microbial flow fields   Despite their importance in many biological, ecological and physical
processes, microorganismal fluid flows under tight confinement have not been
investigated experimentally. Strong screening of Stokelets in this geometry
suggests that the flow fields of different microorganisms should be universally
dominated by the 2D source dipole from the swimmer's finite-size body.
Confinement therefore is poised to collapse differences across microorganisms,
that are instead well-established in bulk. Here we combine experiments and
theoretical modelling to show that, in general, this is not correct. Our
results demonstrate that potentially minute details like microswimmers'
spinning and the physical arrangement of the propulsion appendages have in fact
a leading role in setting qualitative topological properties of the
hydrodynamic flow fields of micro-swimmers under confinement. This is well
captured by an effective 2D model, even under relatively weak confinement.
These results imply that active confined hydrodynamics is much richer than in
bulk, and depends in a subtle manner on size, shape and propulsion mechanisms
of the active components.

31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
6
The categories of this paper are: astro-ph
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
18
The categories of this paper are: econ
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg