Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Bistability in the wake of a wavy cylinder   We investigate the wake dynamics of an optimally designed wavy cylinder that
completely suppresses the K\'arm\'an vortex shedding. Such a wavy cylinder is
forced to oscillate with a sinusoidal motion in the crossflow direction.
Examination of the lift force spectrum reveals that a critical forcing
frequency exists, below which the flow control effectiveness of the wavy
cylinder is retained, and beyond which the inherent vortex shedding resurrects.
Moreover, the resurrected unsteady vortex shedding can persist even without
sustained forcing, leading to the loss of control efficacy. This suggests that
in addition to the steady state developed from uniform initial condition, an
oscillatory state exists in the wake of wavy cylinder if the initial state is
sufficiently perturbed. The discovery of the bistable states calls for
examination of the flow control effectiveness of the wavy cylinder in more
complicated inflow conditions.

24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
2
The categories of this paper are: math
29
The categories of this paper are: funct-an
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
10
The categories of this paper are: q-bio
17
The categories of this paper are: q-fin