Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On Ohm's law in reduced plasma fluid models   Drift-reduced MHD models are widely used to study magnetised plasma
phenomena, in particular for magnetically confined fusion applications, as well
as in solar and astrophysical research. This letter discusses the choice of
Ohm's law in these models, the resulting dispersion relations for the dynamics
parallel to the magnetic field, and the implications for numerical simulations.
We find that if electron pressure is included in Ohm's law, then both
electromagnetic and finite electron mass effects must also be included in order
to obtain physical dispersion relations. A simple modification to the plasma
vorticity is also found which improves handling of low density regions, of
particular relevance to the simulation of the boundary region of magnetised
plasmas.

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The categories of this paper are: hep-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
19
The categories of this paper are: eess
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys