Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Phase-based control of periodic fluid flows   Fluid flows play a central role in scientific and technological development,
and many of these flows are characterized by a dominant oscillation, such as
the vortex shedding in the wake of nearly all transportation vehicles. The
ability to control vortex shedding is critical to improve the aerodynamic
performance of these unsteady fluid flow systems. This goal requires precise
characterization of how perturbations affect the long-time phase of the
oscillatory flow, as well as the ability to control transient behaviors. In
this work, we develop an energy-efficient flow control strategy to rapidly
alter the oscillation phase of time-periodic fluid flows, leveraging theory
developed for periodic biological systems. First, we perform a
phase-sensitivity analysis to construct a reduced-order model for the response
of the flow oscillation to impulsive control inputs at various phases. Next, we
introduce two control strategies for real-time phase control based on the
phase-sensitivity function: 1) optimal phase control, obtained by solving the
Euler-Lagrange equations as a two-point boundary value problem, and 2)
model-predictive control (MPC). Our approach is demonstrated for two unsteady
flow systems, the incompressible laminar flow past a circular cylinder and the
flow past an airfoil. We show that effective phase control may be achieved with
several actuation strategies, including blowing and rotary control. Moreover,
our control approach uses realistic measurements of the lift force on the body,
rather than requiring high-dimensional measurements of the full flow field.

19
The categories of this paper are: eess
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
28
The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
8
The categories of this paper are: hep-ex
26
The categories of this paper are: bayes-an