Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Head-on collisions of dense granular jets   When a dense stream of dry, non-cohesive grains hits a fixed target, a
collimated sheet is ejected from the impact region, very similar to what
happens for a stream of water. In this study, as a continuation of the
investigation why such remarkably different incident fluids produce such
similar ejecta, we use discrete particle simulations to collide two
unequal-width granular jets head-on in two dimensions. In addition to the
familiar coherent ejecta, we observe that the impact produces a far less
familiar quasi-steady-state corresponding to a uniformly translating free
surface and flow field. Upon repeating such impacts with multiple continuum
fluid simulations, we show that this translational speed is controlled only by
the total energy dissipation rate to the power $1.5$, and is independent of the
details of the jet composition. Our findings, together with those from impacts
against fixed targets, challenge the principle of scattering in which material
composition is inferred from observing the ejecta produced during impact.

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The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
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The categories of this paper are: plasm-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
1
The categories of this paper are: cs
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The categories of this paper are: acc-phys
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The categories of this paper are: q-fin
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The categories of this paper are: supr-con