Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Analysis and boundary condition of the lattice Boltzmann BGK model with
  two velocity components   In this paper, we study the two dimensional lattice Boltzmann BGK model
(LBGK) by analytically solving a simple flow in a 2~-D channel. The flow is
driven by the movement of upper boundary with vertical injection fluid at the
porous boundaries. The velocity profile is shown to satisfy a second-order
finite-difference form of the simplified incompressible Navier-Stokes equation.
With the analysis, different boundary conditions can be studied theoretically.
A momentum exchange principle is also revealed at the boundaries. A general
boundary condition for any given velocity boundary is proposed based on the
analysis.

20
The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga