Biology subjects

Kolomenskiy, D.

Publications and source records attributed to Kolomenskiy, D..

3 recordsLinked to original sources

bioRxiv2024

An experimental study of free flight kinematics in a miniature parasitoid wasp Trichogramma telengai

Body size is the major factor to the flight mechanics in animals. To fly at low Reynolds numbers, miniature insects have adaptations in kinematics and wing structure. Many microinsects have bristled wings, which reduce inertia and power requirements when providing good aerodynamic efficiency. But both bristled and membranous-winged microinsects fly at Reynolds numbers of about 10. Yet, the kinematics of the smallest known membranous-winged species have not been studied sufficiently. The available data are limited to the forewings of a relatively large parasitoid wasp Encarsia formosa. We studied kinematics of wings and body and flight performance in one of the smallest membranous-winged wasps, Trichogramma telengai (0.5 mm body length, Re = 12). T. telengai reaches 29 cm s-1 speed and 7 m s-2 acceleration in horizontal flight which are comparable with the flight performance of other microinsects. The wingbeat cycle is characterized by high frequency (283 Hz) and stroke amplitude (149{degrees}) and includes U-shaped strokes at high angles of attack and prolonged clap-and-fling. The hindwings move with a slight phase shift and smaller amplitude than the forewings. T. telengai differs from large membranous-winged insects and miniature featherwing beetles in kinematics, but it is fundamentally similar to E. formosa (Re = 18, membranous wings) and thrips Frankliniella occidentalis (Re = 15, bristled wings). We showed that, at Re {approx} 101, both membranous and bristled-winged insects have sufficient flight performance. Further study of the bristled-winged insects will make it possible to define the size limits of effectiveness of different wing structures.

biophysics↗

bioRxiv2021

A novel flight style allowing the smallest featherwing beetles to excel

Flight speed generally correlates positively with animal body size1. Surprisingly, miniature featherwing beetles can fly at speeds and accelerations of insects three times as large2. We show here that this performance results from a previously unknown type of wing motion. Our experiment combines three-dimensional reconstructions of morphology and kinematics in one of the smallest insects, Paratuposa placentis (body length 395 m). The flapping bristled wing follows a pronounced figure-eight loop that consists of subperpendicular up and down strokes followed by claps at stroke reversals, above and below the body. Computational analyses suggest a functional decomposition of the flapping cycle in two power half strokes producing a large upward force and two down-dragging recovery half strokes. In contrast to heavier membranous wings, the motion of bristled wings of the same size requires little inertial power. Muscle mechanical power requirements thus remain positive throughout the wing beat cycle, making elastic energy storage obsolete. This novel flight style evolved during miniaturization may compensate for costs associated with air viscosity and helps explain how extremely small insects preserved superb aerial performance during miniaturization. Incorporating this flight style in artificial flappers is a challenge for designers of micro aerial vehicles.

zoology↗

bioRxiv2019

On the energetics and stability of a minimal fish school

The physical basis for fish schooling is examined using three-dimensional numerical simulations of a pair of swimming fish, with kinematics and geometry obtained from experimental data. Energy expenditure and efficiency are evaluated using a cost of transport function, while the effect of schooling on the stability of each swimmer is examined by probing the lateral force and the lateral and longitudinal force fluctuations. We construct full maps of the aforementioned quantities as functions of the spatial pattern of the swimming fish pair and show that both energy expenditure and stability can be invoked as possible reasons for the swimming patterns and tail-beat synchronization observed in real fish. Our results suggest that high cost of transport zones should be avoided by the fish. Wake capture may be energetically unfavorable in the absence of kinematic adjustment. We hereby hypothesize that fish may restrain from wake capturing and, instead, adopt side-to-side configuration as a conservative strategy, when the conditions of wake energy harvesting are not satisfied. To maintain a stable school configuration, compromise between propulsive efficiency and stability, as well as between school members, ought to be considered.

biophysics↗