Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A two-dimensional model of low-Reynolds number swimming beneath a free
  surface   Biological organisms swimming at low Reynolds number are often influenced by
the presence of rigid boundaries and soft interfaces. In this paper we present
an analysis of locomotion near a free surface with surface tension. Using a
simplified two-dimensional singularity model, and combining a complex variable
approach with conformal mapping techniques, we demonstrate that the deformation
of a free surface can be harnessed to produce steady locomotion parallel to the
interface. The crucial physical ingredient lies in the nonlinear hydrodynamic
coupling between the disturbance flow created by the swimmer and the free
boundary problem at the fluid surface.

17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
15
The categories of this paper are: nucl-ex
2
The categories of this paper are: math
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
0
The categories of this paper are: hep-ph
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas