Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: An angular momentum conserving Affine-Particle-In-Cell method   We present a new technique for transferring momentum and velocity between
particles and grid with Particle-In-Cell (PIC) calculations which we call
Affine-Particle-In-Cell (APIC). APIC represents particle velocities as locally
affine, rather than locally constant as in traditional PIC. We show that this
representation allows APIC to conserve linear and angular momentum across
transfers while also dramatically reducing numerical diffusion usually
associated with PIC. Notably, conservation is achieved with lumped mass, as
opposed to the more commonly used Fluid Implicit Particle (FLIP) transfers
which require a 'full' mass matrix for exact conservation. Furthermore, unlike
FLIP, APIC retains a filtering property of the original PIC and thus does not
accumulate velocity modes on particles as FLIP does. In particular, we
demonstrate that APIC does not experience velocity instabilities that are
characteristic of FLIP in a number of Material Point Method (MPM)
hyperelasticity calculations. Lastly, we demonstrate that when combined with
the midpoint rule for implicit update of grid momentum that linear and angular
momentum are exactly conserved.

20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
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The categories of this paper are: stat
30
The categories of this paper are: q-alg
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con