Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Aeroelastic characterisation of a bio-inspired flapping membrane wing   Natural fliers like bats exploit the complex fluid-structure interaction
between their flexible membrane wings and the air with great ease. Yet,
replicating and scaling the balance between the structural and fluid-dynamical
parameters of unsteady membrane wings for engineering applications remains
challenging. In this study, we introduce a novel bio-inspired membrane wing
design and systematically investigate the fluid-structure interactions of
flapping membrane wings. The membrane wing can passively camber and its leading
and trailing edges rotate with respect to the stroke plane. We find optimal
combinations of the membrane properties and flapping kinematics that
out-perform their rigid counterparts both in terms of increased stroke-average
lift and efficiency but the improvements are not persistent over the entire
input parameter space. The lift and efficiency optima occur at different angles
of attack and effective membrane stiffnesses which we characterise with the
aeroelastic number. At optimal aeroelastic numbers, the membrane has a moderate
camber between 15% and 20% and its leading and trailing edges align favourably
with the flow. Higher camber at lower aeroelastic numbers leads to reduced
aerodynamic performance due to negative angles of attack at the leading edge
and an over-rotation of the trailing edge. Most of the performance gain of the
membrane wings with respect to rigid wings is achieved in the second half of
the stroke when the wing is decelerating. The stroke-maximum camber is reached
around mid-stroke but is sustained during most of the remainder of the stroke
which leads to an increase in lift and a reduction in power. Our results show
that combining the effect of variable stiffness and angle of attack variation
can significantly enhance the aerodynamic performance of membrane wings and has
the potential to improve the control capabilities of micro air vehicles.

16
The categories of this paper are: stat
4
The categories of this paper are: cond-mat
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
8
The categories of this paper are: hep-ex
23
The categories of this paper are: solv-int
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg
37
The categories of this paper are: supr-con