Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: A simple algorithm to implement jump boundary conditions within the
  lattice Boltzmann method
13
The categories of this paper are: quant-ph
19
The categories of this paper are: eess
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
22
The categories of this paper are: chao-dyn
8
The categories of this paper are: hep-ex
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ