Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Turbulent Drag Reduction of polyelectrolyte (DNA) solutions: relation
  with the elongational viscosity   We report measurements of turbulent drag reduction of two different
polyelectrolyte solutions: DNA and hydrolyzed Polyacrylamide. Changing the salt
concentration in the solutions allows us to change the flexibility of the
polymer chains. For both polymers the amount of drag reduction was found to
increase with the flexibility. Rheological studies reveal that the elongational
viscosity of the solutions increases simultaneously. Hence we conclude that the
elongational viscosity is the pertinent macroscopic quantity to describe the
ability of a polymer to cause turbulent drag reduction.

20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
9
The categories of this paper are: nlin
17
The categories of this paper are: q-fin
2
The categories of this paper are: math
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
8
The categories of this paper are: hep-ex