Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lyapunov instability and collective tangent space dynamics of fluids   The phase space trajectories of many body systems charateristic of simple
fluids are highly unstable. We quantify this instability by a set of Lyapunov
exponents, which are the rates of exponential divergence, or convergence, of
initial (infinitesimal) perturbations along carefully selected directions in
phase space. It is demonstrated that the perturbation associated with the
maximum Lyapunov exponent is localized in space. This localization persists in
the large-particle limit, regardless of the interaction potential. The
perturbations belonging to the smallest positive exponents, however, are
sensitive to the potential. For hard particles they form well-defined
long-wavelength modes. The modes could not be observed for systems interacting
with a soft potential due to surprisingly large fluctuations of the local
time-dependent exponents.

33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
16
The categories of this paper are: stat
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org