Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: How does altering synchronization of pitching parallel foils change
  their wake dynamics?   This study was inspired from the swimming habits of red nose tetra fish that
prefer side-by-side configurations and exhibit changes to their synchronization
mid-swimming. Using numerical simulations, alterations to the unsteady wake
dynamics imposed by abrupt changes in the phase angle between two pitching
side-by-side foils were examined at Reynolds number of 4;000 and Strouhal
number of 0:50. Four hybrid modes were considered in thisstudy with two modes
representing an abrupt phase change by pi during the 20th cycle. The other two
modes represented a simplified case of burst-and-coast swimming, in which there
was a brief (2 oscillation periods) suspension of oscillations before imposing
a change in phase angle. In all cases, the foils initially performed
out-of-phase pitching, and then they started their in-phase motion by either
performing the upstroke or down-stroke first. This kinematic change resulted in
the formation and growth of a secondary vortex street in between two primary
streets, which enabled and maintained a split wake configuration. Furthermore,
the phase switching altered the pressure levels on the top and bottom surfaces
of both foils to almost similar levels, which attributed to a reduction in the
side-force. The growth rate of the secondary vortex street remained consistent
for all four hybrid modes.

21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
19
The categories of this paper are: eess
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
18
The categories of this paper are: econ
37
The categories of this paper are: supr-con
16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
36
The categories of this paper are: cmp-lg
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc