Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Direct observation of hydrodynamic instabilities in driven non-uniform
  colloidal dispersions   A Rayleigh-Taylor-like instability of a dense colloidal layer under gravity
in a capillary of microfluidic dimensions is considered. We access all relevant
lengthscales with particle-level microscopy and computer simulations which
incorporate long-range hydrodynamic interactions between the particles. By
tuning the gravitational driving force, we reveal a mechanism whose growth is
connected to the fluctuations of specific wavelengths, non-linear pattern
formation and subsequent diffusion-dominated relaxation. Our linear stability
theory captures the initial regime and thus predicts mixing conditions, with
important implications for fields ranging from biology to nanotechnology.

37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
18
The categories of this paper are: econ