Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fluid-solid Floquet stability analysis of self-propelled heaving foils   We investigate the role of linear mechanisms in the emergence of nonlinear
horizontal self-propelled states of a heaving foil in a quiescent fluid. Two
states are analyzed: a periodic state of unidirectional motion and a
quasi-periodic state of slow back & forth motion around a mean horizontal
position. The states emergence is explained through a fluid-solid Floquet
stability analysis of the non-propulsive symmetric base solution. Unlike a
purely-hydrodynamic analysis, our analysis accurately determine the locomotion
states onset. An unstable synchronous mode is found when the unidirectional
propulsive solution is observed. The obtained mode has a propulsive character,
featuring a mean horizontal velocity and an asymmetric flow that generates a
horizontal force accelerating the foil. An unstable asynchronous mode, also
featuring flow asymmetry and a non-zero velocity, is found when the back &
forth state is observed. Its associated complex multiplier introduces a slow
modulation of the flapping period, agreeing with the quasi-periodic nature of
the back & forth regime. The temporal evolution of this perturbation shows how
the horizontal force exerted by the flow is alternatively propulsive or
resistive over a slow period. For both modes, an analysis of the velocity and
force perturbation time-averaged over the flapping period is used to establish
physical instability criteria. The behaviour for large solid-to-fluid density
ratio of the modes is thus analyzed. The asynchronous fluid-solid mode
converges towards the purely-hydrodynamic one, whereas the synchronous mode
becomes marginally unstable in our analysis not converging to the
purely-hydrodynamic analysis where it is never destabilised.

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The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
11
The categories of this paper are: hep-lat
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
15
The categories of this paper are: nucl-ex
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
34
The categories of this paper are: chem-ph
18
The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th