Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fluid breakup during simultaneous two-phase flow through a
  three-dimensional porous medium   We use confocal microscopy to directly visualize the simultaneous flow of
both a wetting and a non-wetting fluid through a model three-dimensional (3D)
porous medium. We find that, for small flow rates, both fluids flow through
unchanging, distinct, connected 3D pathways; in stark contrast, at sufficiently
large flow rates, the non-wetting fluid is broken up into discrete ganglia. By
performing experiments over a range of flow rates, using fluids of different
viscosities, and with porous media having different geometries, we show that
this transition can be characterized by a state diagram that depends on the
capillary numbers of both fluids, suggesting that it is controlled by the
competition between the viscous forces exerted on the flowing oil and the
capillary forces at the pore scale. Our results thus help elucidate the diverse
range of behaviors that arise in two-phase flow through a 3D porous medium.

31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
29
The categories of this paper are: funct-an
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
35
The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol