Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unsteady three-dimensional boundary element method for self-propelled
  bio-inspired locomotion   An unsteady three-dimensional boundary element method is developed to provide
fast calculations of biological and bio-inspired self-propelled locomotion. The
approach uniquely combines an unsteady three-dimensional boundary element
method, a boundary layer solver and self-propelled equations of motion. This
novel implementation allows for the self-propelled speed, power, efficiency and
economy to be accurately calculated. A Dirichlet formulation is used with a
combination of constant strength source and doublet elements to represent a
deforming body with a nonlinearly deforming wake. The wake elements are
desingularized to numerically stabilize the evolution of the wake vorticity.
Weak coupling is used in solving the equations of motion and in the boundary
layer solution. The boundary layer solver models both laminar and turbulent
behavior along the deforming body to estimate the total skin friction drag
acting on the body. The results from the method are validated with analytical
solutions, computations and experiments. Finally, a bio-inspired self-propelled
undulatory fin is modeled. The computed self-propelled speeds and wake
structures agree well with previous experiments. The computations go beyond the
experiments to gain further insight into the propulsive efficiency for
self-propelled undulating fins. It is found that the undulating fin produces a
time-averaged momentum jet at 76% of the span that accelerates fluid in the
streamwise direction and in turn generates thrust. Additionally, it is
discovered that high amplitude motions suppress the formation of a bifurcating
momentum jet and instead form a single core jet. Consequently, this maximizes
the amount of streamwise momentum compared to the amount of wasted lateral
momentum and leads to a propulsive efficiency of 78% during self-propelled
locomotion.

2
The categories of this paper are: math
15
The categories of this paper are: nucl-ex
19
The categories of this paper are: eess
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
6
The categories of this paper are: astro-ph
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex