258 research outputs found
The Hungry Fly: Hydrodynamics of feeding in the common house fly
A large number of insect species feed primarily on a fluid diet. To do so,
they must overcome the numerous challenges that arise in the design of
high-efficiency, miniature pumps. Although the morphology of insect feeding
structures has been described for decades, their dynamics remain largely
unknown even in the most well studied species (e.g. fruit fly). Here, in the
fluid dynamics video, we demonstrate in-vivo imaging and microsurgery to
elucidate the design principles of feeding structures of the common house fly.
Using high-resolution X-ray absorption microscopy, we record in-vivo flow of
sucrose solutions through the body over many hours during fly feeding.
Borrowing from microsurgery techniques common in neurophysiology, we are able
to perturb the pump to a stall position and thus evaluate function under load
conditions. Furthermore, fluid viscosity-dependent feedback is observed for
optimal pump performance. As the gut of the fly starts to fill up, feedback
from the stretch receptors in the cuticle dictates the effective flow rate.
Finally, via comparative analysis between the housefly, blow fly, fruit fly and
bumble bees, we highlight the common design principles and the role of
interfacial phenomena in feeding.Comment: Two videos are included with this submissio
Rapid behavioral transitions produce chaotic mixing by a planktonic microswimmer
Despite their vast morphological diversity, many invertebrates have similar
larval forms characterized by ciliary bands, innervated arrays of beating cilia
that facilitate swimming and feeding. Hydrodynamics suggests that these bands
should tightly constrain the behavioral strategies available to the larvae;
however, their apparent ubiquity suggests that these bands also confer
substantial adaptive advantages. Here, we use hydrodynamic techniques to
investigate "blinking," an unusual behavioral phenomenon observed in many
invertebrate larvae in which ciliary bands across the body rapidly change
beating direction and produce transient rearrangement of the local flow field.
Using a general theoretical model combined with quantitative experiments on
starfish larvae, we find that the natural rhythm of larval blinking is
hydrodynamically optimal for inducing strong mixing of the local fluid
environment due to transient streamline crossing, thereby maximizing the
larvae's overall feeding rate. Our results are consistent with previous
hypotheses that filter feeding organisms may use chaotic mixing dynamics to
overcome circulation constraints in viscous environments, and it suggests
physical underpinnings for complex neurally-driven behaviors in early-divergent
animals.Comment: 20 pages, 4 figure
Synchronous Droplet Microfluidics: One "Clock" to rule them all
Controlling fluid droplets efficiently in the microscale is of great interest
both from a basic science and a technology perspective. We have designed and
developed a general-purpose, highly scalable microfluidic control strategy
through a single global clock signal that enables synchronous control of
arbitrary number of droplets in a planar geometry. A rotating precessive
magnetic field provides a global clock signal, enabling simultaneous control of
droplet position, velocity and trajectories. Here, in this fluid dynamics
video, we explain the main physics of this new microfluidic concept. Video data
from droplets moving in sync in different fluidic circuits are included. The
experimental setup is described and video data is analyzed to provide a
detailed view of the time-dynamics of propagating droplets. Finally, we explore
the operational limits of this concept, scaling and phase diagram with physical
regime diagram.Comment: two video files include
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