Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effective velocity boundary condition at a mixed slip surface   This paper studies the nature of the effective velocity boundary conditions
for liquid flow over a plane boundary on which small free-slip islands are
randomly distributed. It is found that, to lowest order in the area fraction
$\beta$ covered by free-slip regions with characteristic size $a$, a
macroscopic Navier-type slip condition emerges with a slip length of the order
of $a\beta$. The study is motivated by recent experiments which suggest that
gas nano-bubbles may form on solid walls and may be responsible for the
appearance of a partial slip boundary conditions for liquid flow. The results
are also relevant for ultra-hydrophobic surfaces exploiting the so-called
``lotus effect''.

36
The categories of this paper are: cmp-lg
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
20
The categories of this paper are: acc-phys
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th