Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Linking continuum-scale state of wetting to pore-scale contact angles in
  porous media   Wetting phenomena play a key role in flows through porous media. Relative
permeability and capillary pressure-saturation functions show a high
sensitivity to wettability, which has different definitions at the continuum-
and pore-scale. At the continuum-scale, the state of wetting is defined as
Amott-Harvey or USBM (United States Bureau of Mines) by capillary pressure
drainage and imbibition cycles. At the pore-scale, the concept of contact angle
is used, which until recently was not experimentally possible to determine
within an opaque porous medium. Recent progress on measurements of pore-scale
contact angles by X-ray computed micro-tomography has therefore attracted
significant attention in various research communities. In this work, the
Gauss-Bonnet theorem is applied to provide a direct link between capillary
pressure saturation $P_c(S_w)$ data and measured distributions of pore-scale
contact angles. We propose that the wetting state of a porous medium can be
described in terms of geometrical arguments that constrain the morphological
state of immiscible fluids. The constraint describes the range of possible
contact angles and interfacial curvatures that can exist for a given system. We
present measurements in a tested sandstone for which the USBM index,
$P_c(S_w)$, and pore-scale contact angles are measured. Additional studies are
also performed using two-phase Lattice Boltzmann simulations to test a wider
range of wetting conditions. We show that mean pore-scale contact angle
measurements can be predicted from petrophysical data within a few differences.
This provides a general framework on how continuum-scale data can be used to
describe the geometrical state of fluids within porous media.

17
The categories of this paper are: q-fin
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
12
The categories of this paper are: nucl-th
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
25
The categories of this paper are: patt-sol
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas