Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Inertial hydrodynamic ratchet: Rectification of colloidal flow in tubes
  of variable diameter   We investigate analytically a microfluidic device consisting of a tube with
non-uniform but spatially periodic diameter, where a fluid driven back and
forth by a pump carries colloidal particles. Although the net flow of the fluid
is zero, the particles move preferentially in one direction due to ratchet
mechanism, which occurs by simultaneous effect of inertial hydrodynamics and
Brownian motion. We show that the average current is strongly sensitive to
particle size, thus facilitating colloidal particle sorting.

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The categories of this paper are: cs
15
The categories of this paper are: nucl-ex
10
The categories of this paper are: q-bio
23
The categories of this paper are: solv-int
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The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
19
The categories of this paper are: eess
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The categories of this paper are: bayes-an
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The categories of this paper are: astro-ph
37
The categories of this paper are: supr-con
36
The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn