Searcharxiv⌕ Search
Home/Archive/arXiv

arXiv · physics/0610064

The flow generated by an active olfactory system of the red swamp crayfish

P. Denissenko·S. Lukaschuk·T. Breithaupt
View original source ↗Read source document ↗Export metadata ↓

Abstract

Crayfish are nocturnal animals that mainly rely on their chemoreceptors to locate food. On a crayfish scale chemical stimuli received from a distant source are dispersed by an ambient flow rather than molecular diffusion. When the flow is weak or absent, food search can be facilitated by currents generated by the animal itself. Crayfish employ their anterior fan organs to produce a variety of flow patterns. Here we study the flow generated by Procambarus clarkii in response to odour stimulation. We found that while searching for food the crayfish generates one or two outward jets. These jets create an inflow which draws odour to the crayfish's anterior chemoreceptors. We quantified velocity fields in the inflow region using Particle Image Velocimetry. The results show that the inflow velocity decreases proportionally to the inverse distance from the animal so that it takes about a minute for an odour plume to reach the animal's chemoreceptors from a distance of 10 cm. We compare the inflow generated by live crayfish with that produced by a mimicking device, a phantom. The phantom consisted of two nozzles and an inlet providing two jets and a sink so that the overall mass flux was zero. The use of a phantom enabled us to analyze the inflow at various jet parameters. We showed that variation of the jets' directions and relative intensities allows changing the direction of odour attraction. These results provide a rationale for biomimetic robot design. We discuss sensitivity and efficiency of such a robot.

Explore related subjects

physics.flu-dynphysics.bio-ph

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P. Denissenko, S. Lukaschuk, T. Breithaupt. 2007-06-21. The flow generated by an active olfactory system of the red swamp crayfish. https://arxiv.org/abs/physics/0610064

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Statistical State Dynamics based study of turbulence in Eady fronts. Part 1. Instability

The streamwise roll and streak structure (RSS) is prominent in observations of the planetary boundary layer in the atmosphere and ocean and in unstratified wall-bounded shear flows. Although the RSS in these systems is structurally similar, the mechanism forming and maintaining the RSS in both remains controversial. This study demonstrates that the same turbulence-sustaining mechanism identified to underlie the RSS in the Statistical State Dynamics (SSD) formulation of unstratified wall-bounded shear flow dynamics (Farrell & Ioannou 2012; Farrell et al. 2016) also operates in the Eady front. We analyze the mechanism by which turbulence and symmetric instability interact to form the RSS in the baroclinic stratified Eady front model by adapting to the Eady front problem the stability analysis of the second order closure of the SSD used previously to study roll formation in unstratified wall-bounded shear flows. Our findings advance mechanistic understanding of RSS formation in the turbulent geostrophic front regime and establish foundational parallels between geophysical turbulent front dynamics and turbulence dynamics in engineering-scale shear flows.

physics.flu-dyn↗
arXiv2026

Statistical state dynamics based study of turbulent Eady fronts. Part 2. Finite amplitude equilibria

Streamwise roll circulations commonly observed in frontal regions are primary agents of momentum and tracer transport in the planetary boundary layer (PBL) both in the atmosphere and ocean. Traditionally, the formation of the streamwise roll/streak structure (RSS) has been ascribed to symmetric instability (SI). In part 1, we studied RSS formation in the classical Eady front problem using statistical state dynamics (SSD), which allows incorporating the Reynolds stress (RS) torque instability mechanism together with SI in the dynamics underlying RSS formation. We found using SSD theory that the RS torque mechanism acts synergistically with the SI mechanism in forcing symmetric circulations in fronts when Richardson number Ri < 1, and also that the turbulence-mediated RS torque mechanism supports RSS formation in fronts with Ri > 1 for which the SI mechanism does not operate. Although SI theory provides an explanation for initial roll formation, it leaves open the question of RSS equilibration. An advantage of the SSD formulation of RSS dynamics is that it consistently incorporates the equilibration process. In this paper, we extend perturbation analysis of RSS dynamics in the SSD framework to a nonlinear analysis to understand roll formation, equilibration, and maintenance in the turbulent RSS regime.

physics.flu-dyn↗
arXiv2026

Small-Scale Dynamo for Full Spectrum of Hydrodynamic Turbulence in Kazantsev Model

A method is proposed for computing coefficients in the Kazantsev equation of small-scale dynamo for the full spectrum of hydromagnetic turbulence comprising the inertial range together with the range of viscous dissipation. The dynamo equation with so-defined coefficients is solved numerically for magnetic (Rm) and hydrodynamic (Re) Reynolds numbers from $10^2$ to $10^8$. The threshold value ${\rm Rm}_c$ for onset of dynamo increases initially with Re but then saturates at a constant value of ${\rm Rm}_c \simeq 300$ for ${\rm Re}\geq 10^5$. In the case of small Prandtl number Pm = Rm/Re << 1, the field growth rate is also small and depends logarithmically on Rm. In this case, the magnetic energy spectrum peaks around the scale of Ohmic dissipation, which decreases with increasing Pm. The decrease stops at the scale of viscous dissipation while the growth rate increases sharply when Pm approaches the value of one. The increase in the growth rate proceeds to ${\rm Pm} > 1$ but slows down and then saturates at a value somewhat below the inverse lifetime of most short-living eddies. An explanation of the results is proposed.

physics.flu-dyn↗