Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Agglomeration of Charged Nanopowders in Suspensions   The aim of this work is to understand agglomeration of charged powders
suspended in nonpolar fluids. The concerted influence of electromagnetic,
hydrodynamic and van der Waals forces as well as Brownian motion leads to a
complex agglomeration behaviour which depends on several parameters, e.g., the
ratios of electric charges, particle sizes, temperature and concentrations of
the particles. Both experimental and theoretical considerations are presented.

22
The categories of this paper are: chao-dyn
31
The categories of this paper are: ao-sci
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
28
The categories of this paper are: alg-geom
24
The categories of this paper are: dg-ga
2
The categories of this paper are: math
7
The categories of this paper are: hep-th
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
29
The categories of this paper are: funct-an
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg