Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fluid drag reduction by magnetic confinement   The frictional forces of a viscous liquid flow are a major energy loss issue
and severely limit microfluidics practical use. Reducing this drag by more than
a few tens of percent remain illusive. Here, we show how cylindrical
liquid-in-liquid flow leads to drag reduction of 60-99% for sub mm and mm sized
channels, irrespective of whether the viscosity of the transported liquid is
larger or smaller than that of the encapsulating one. In contrast to
lubrication or sheath flow, we do not require the continuous flow of the
encapsulating lubricant, here made up of a ferrofluid held in place by magnetic
forces. In a laminar flow model with appropriate boundary conditions, we
introduce a modified Reynolds number with a scaling that depends on geometrical
factors and viscosity ratio of the two liquids. It explains our whole range of
data and reveal the key design parameters for optimizing the drag reduction
values. Our results therefore open the route to microfluidics designs with
pressure gradients possibly reduced by orders of magnitudes.

26
The categories of this paper are: bayes-an
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th