Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Flow rate measurement in stacks with cyclonic flow_-_Error estimations
  using CFD modelling
2
The categories of this paper are: math
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
31
The categories of this paper are: ao-sci
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat