scholarly journals Do terrestrial hermit crabs sniff? Air flow and odorant capture by flicking antennules

2016 ◽  
Vol 13 (114) ◽  
pp. 20150850 ◽  
Author(s):  
Lindsay D. Waldrop ◽  
M. A. R. Koehl
Keyword(s):  
Particle Image Velocimetry ◽  
Particle Image ◽  
Hermit Crabs ◽  
Fine Scale ◽  
Computational Simulations ◽  
Return Stroke ◽  
Image Velocimetry ◽  
Olfactory Organs ◽  
Surrounding Fluid ◽  
Capture Rates

Capture of odorant molecules by olfactory organs from the surrounding fluid is the first step of smelling. Sniffing intermittently moves fluid across sensory surfaces, increasing delivery rates of molecules to chemosensory receptors and providing discrete odour samples. Aquatic malacostracan crustaceans sniff by flicking olfactory antennules bearing arrays of chemosensory hairs (aesthetascs), capturing water in the arrays during downstroke and holding the sample during return stroke. Terrestrial malacostracans also flick antennules, but how their flicking affects odour capture from air is not understood. The terrestrial hermit crab, Coenobita rugosus , uses antennules bearing shingle-shaped aesthetascs to capture odours. We used particle image velocimetry to measure fine-scale fluid flow relative to a dynamically scaled physical model of a flicking antennule, and computational simulations to calculate diffusion to aesthetascs by odorant molecules carried in that flow. Air does not flow into the aesthetasc array during flick downstrokes or recovery strokes. Odorants are captured from air flowing around the outside of the array during flick downstrokes, when aesthetascs face upstream and molecule capture rates are 21% higher than for stationary antennules. Bursts of flicking followed by pauses deliver discrete odour samples to olfactory sensors, causing intermittency in odour capture by a different mechanism than aquatic crustaceans use.

Water Synthetic Jet Driven by a Piezoelectric Actuator – LIF and PIV Experiments

2015 ◽  
Vol 1104 ◽  
pp. 45-50 ◽  
Author(s):  
Zuzana Broučková ◽  
Shu Shen Hsu ◽  
An Bang Wang ◽  
Zdeněk Trávníček
Keyword(s):  
Reynolds Number ◽  
Particle Image Velocimetry ◽  
Piezoelectric Actuator ◽  
Particle Image ◽  
Three Dimensional ◽  
Laser Induced Fluorescence ◽  
Synthetic Jet ◽  
Fluid Exchange ◽  
Image Velocimetry ◽  
Surrounding Fluid

A synthetic jet (SJ) is a fluid jet flow generated from fluid oscillations during a periodical fluid exchange between an actuator cavity and surrounding fluid. A water synthetic jet was generated from submerged piezoelectric-driven SJ actuator. The actuator slot width was 0.36 mm. The experiments were performed using laser induced fluorescence (LIF) flow visualization and particle image velocimetry (PIV) techniques, both in a phase locked setup. The LIF visualization was used to demonstrate three-dimensional nature of the SJ formation process and to estimate SJ velocity. The PIV experiment quantified SJ velocity cycles in chosen plans. The driven frequency was adjusted near the resonance at approximately 46 Hz. It was evaluated theoretically and confirmed experimentally by means of LIF visualization. The time-mean orifice velocity and the Reynolds number were estimated asU0= 0.07–0.10 m/s andRe= 100–150, respectively.

Stomatopod antennule design: the asymmetry, sampling efficiency and ontogeny of olfactory flicking

2000 ◽  
Vol 203 (24) ◽  
pp. 3795-3808 ◽  
Author(s):  
K.S. Mead ◽  
M.A. Koehl
Keyword(s):  
Particle Image Velocimetry ◽  
Relative Velocity ◽  
Particle Image ◽  
Flow Fields ◽  
Physical Models ◽  
Sampling Efficiency ◽  
Return Stroke ◽  
Velocity Gradients ◽  
Image Velocimetry ◽  
Age Dependent

Many crustaceans detect odors from distant sources using chemosensory sensilla (aesthetascs) on their antennules. The greater the flow of water through arrays of aesthetascs, the faster the access of odorant to receptors inside the aesthetascs. Stomatopods facilitate odorant access by flicking their antennules, thus increasing the relative velocity of the water reaching their aesthetascs. We used dynamically scaled physical models to investigate how aesthetasc size and spacing and antennule flicking velocity affect flow penetration into the simple aesthetasc arrays of the stomatopod Gonodactylaceus mutatus. Particle image velocimetry of flow fields near models of juvenile and adult antennules revealed that velocity gradients around the aesthetascs are steeper during the outward part of the flick than during the return stroke and that the velocity gradients are steeper at the aesthetasc tips than at their bases. More fluid per unit time flows between aesthetasc rows during the outward stroke than during the return stroke, ensuring that odor sampling is pulsatile. During flicking, velocity gradients are steeper near adult aesthetascs than near juvenile aesthetascs, and adults process more fluid per unit time than juveniles. The resulting differences in odorant access can be related to size- and age-dependent changes in stomatopod ecology.

Characterization of Pulsating Submerged Jet—A Particle Image Velocimetry Study

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Harekrishna Yadav ◽  
Atul Srivastava ◽  
Amit Agrawal
Keyword(s):  
Particle Image Velocimetry ◽  
Critical Frequency ◽  
Particle Image ◽  
Near Field ◽  
Reynolds Numbers ◽  
Pulsation Frequency ◽  
Potential Core ◽  
Image Velocimetry ◽  
Pulsating Jet ◽  
Surrounding Fluid

An experimental investigation has been performed to determine the flow characteristics of an axisymmetric submerged water jet with superimposed periodically oscillating flow. The objective of the study is to quantify in detail the near field of a pulsating jet using the particle image velocimetry (PIV) technique. The amplitude and frequency of oscillations are varied separately and the effect of each parameter is determined for a range of Reynolds numbers (ReD = 1602, 2318, and 3600). The experimental results indicate that for a given Reynolds number and amplitude, with an increase in the frequency of pulsation, the vortex formation shifts toward the nozzle exit. The number of vortices also increases with an increase in the jet pulsation frequency. Broadening of the jet and shortening of the potential core length are also observed. This indicates that mixing with the surrounding fluid is higher with pulsating jet even at relatively low Reynolds numbers. It is observed that frequency up to a critical frequency helps increase entrainment of the surrounding fluid. An upper critical frequency beyond which pulsation does not affect the entrainment is also determined. These results should eventually lead to a better understanding of the physical phenomena responsible for enhanced heat transfer rates in the presence of pulsating jets.

Performance Characterization of a Traveling-Wave Electrohydrodynamic Micropump

2008 ◽  
Author(s):  
Brian D. Iverson ◽  
Suresh V. Garimella
Keyword(s):  
Particle Image Velocimetry ◽  
Traveling Wave ◽  
Particle Image ◽  
Velocity Measurements ◽  
Image Velocimetry ◽  
Three Phase ◽  
Spatially Varying ◽  
Wave Device ◽  
Surrounding Fluid

Microscale fluidic manipulation using traveling-wave, induction electrohydrodynamics is demonstrated. A three-phase traveling-wave device fabricated for the experiments provides a temporally and spatially varying electric field which helps induce ions in a fluid subject to a temperature gradient. These ions are moved as the traveling wave propagates, resulting in a drag force being exerted on the surrounding fluid. Repulsion-type electrohydrodynamic flow is visualized in a microchannel of depth 50 μm, and results are presented in terms of velocity measurements using particle image velocimetry.

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