Mobility of free surface in different liquids and its influence on water striders locomotion

Vinnichenko, Nikolay A.; Plaksina, Yulia Yu.; Baranova, Ksenia M.; Pushtaev, Alexey V.; Uvarov, A. V.

doi:10.1007/s10652-018-9577-9

Cited by 14 publications

(5 citation statements)

References 25 publications

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“…The reduced surface tension caused by Microcystis colonies can also directly generate surface flows being directed towards regions of high surface tension (Marangoni effect ( Roché et al., 2014 ; Vinnichenko et al., 2018 ), i.e., a spreading towards Microcystis- free regions. Although we could not directly observe this flow in our experiment as the Marangoni flow was masked by the wind-driven flow, it is ubiquitously present in environmental flows ( Scriven and Sternling, 1960 ).…”

Section: Discussionmentioning

confidence: 99%

Dynamics of Microcystis surface scum formation under different wind conditions: the role of hydrodynamic processes at the air-water interface

Wu,

Rovelli

et al. 2024

Front. Plant Sci.

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Due to climate change, Microcystis blooms occur at increasing frequencies in aquatic ecosystems worldwide. Wind-generated turbulence is a crucial environmental stressor that can vertically disperse the Microcystis surface scum, reducing its light availability. Yet, the interactions of Microcystis scum with the wind-generated hydrodynamic processes, particularly those at the air-water interface, remain poorly understood. Here, we explore the response of Microcystis (including colony size and migration dynamics) to varying magnitudes and durations of intermittent wind disturbances in a mesocosm system. The flow velocities, size of Microcystis colonies, and the areal coverage of the water surface by scum were measured through video observations. Our results demonstrate that low wind speeds increase colony size by providing a stable condition where Microcystis forms a scum layer and aggregates into large colonies at the air-water interface. In contrast, wind disturbances disperse scum and generate turbulence, resulting in smaller colonies with higher magnitudes of wind disturbance. We observed that surface scum can form rapidly following a long period (6 h) of high-magnitude (4.5 m s-1) wind disturbance. Furthermore, our results indicate reduced water surface tension caused by the presence of Microcystis, which can decrease surface flow velocity and counteract wind-driven mixing. The reduced surface tension may also drive lateral convection at the water surface. These findings suggest that Microcystis reduces surface tension, likely by releasing surface-active materials, as an adaptive response to various wind conditions. This could result in an increased rate of surface scum re-formation under wind conditions and potentially facilitate the lateral expansion of scum patches during weak wind periods. This study reveals new insights into how Microcystis copes with different wind conditions and highlights the importance of the air-water interface for Microcystis scum dynamics.

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Section: Discussionmentioning

confidence: 99%

Dynamics of Microcystis surface scum formation under different wind conditions: the role of hydrodynamic processes at the air-water interface

Wu,

Rovelli

et al. 2024

Front. Plant Sci.

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“…Water striders ( Gerris argentatus ) inhabit a wide variety of environments, including the surface of calm and turbulent waters (Andersen, 1982). The cohesive property of water molecules allows the water surface to resist the weight of water striders (Denny, 2004; Vinnichenko et al., 2018). Their bodyweight is supported by the legs, which possess a high level of hydrophobicity (Bush et al., 2007; Caponigro & Eriksen, 1976; Feng et al., 2007; Gao & Jiang, 2004; Hu & Bush, 2010).…”

Section: Introductionmentioning

confidence: 99%

Patterns of load distribution among the legs in small water striders during standing and striding

et al. 2023

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Water striders (Gerris argentatus) move across the water surface by taking advantage of the surface tension, which supports their bodyweight without breaking. During locomotion, the midlegs are primarily responsible for generating thrust, whereas the other legs support the body. Although the aspects of standing and locomotion on the water surface are well understood, relatively fewer studies concerned the coordinated biomechanical movements of the legs. In order to maintain buoyancy of the body on the water surface, the leg positions must be adjusted to distribute the bodyweight appropriately. The present study investigates distribution of the bodyweight on the legs in relatively small water striders. We aimed to understand how loading on the legs changes during sculling that leads to sliding of the body on the water surface. The assistance of all legs at every moment enables the body to maintain its floating during standing and striding. Water striders can achieve a gentle striding through the midlegs driving phase in association with smooth load shifting among their legs, which are positioned in a specific configuration to support the insect on the water surface.

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“…Recent studies of the near-surface convection have shown a significant difference in the flow structure in distilled water and ethanol or silicone oil (Vinnichenko, Uvarov & Plaksina 2014; Vinnichenko et al. 2018 a , b , 2020). Thermocapillary convection is not observed in distilled water.…”

Section: Introductionmentioning

confidence: 99%

“…2012) and forming a kind of elastic surface film, which does not prevent evaporation, but inhibits the surface renewal (Vinnichenko et al. 2018 a ). This hypothesis was first proposed by Frumkin and Levich (Lohse & Zhang 2020) as an alternative to the surface viscosity concept proposed by Boussinesq.…”

Section: Introductionmentioning

confidence: 99%

“…Small moving cells are observed in ultrapure deionized water, whereas distilled or tap water surfaces appear to be stagnant with large cells. Anomalous behaviour of the distilled water surface is thus attributed to the influence of surfactants present in very low concentration even in distilled water (Plaksina et al 2012) and forming a kind of elastic surface film, which does not prevent evaporation, but inhibits the surface renewal (Vinnichenko et al 2018a). This hypothesis was first proposed by Frumkin and Levich (Lohse & Zhang 2020) as an alternative to the surface viscosity concept proposed by Boussinesq.…”

Section: Introductionmentioning

confidence: 99%

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Horizontal convective flow from a line heat source located at the liquid–gas interface in presence of surface film

et al. 2022

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Development of the convective flow from a line heat source located at the liquid surface is studied for the case when thermocapillary convection is inhibited by the surface film. Surface film is formed by small amounts of surfactants present in non-deionized (distilled or natural) water. It imposes a no-slip boundary condition for velocity at the surface and determines the fluid dynamics of the surface layer. For the heat source located at the surface, the vertical stratification is stable and the flow is driven by a horizontal pressure gradient, formed by non-uniform heating of the liquid along the surface. Experimental studies include measurements of velocity fields using particle image velocimetry, surface relief measurements using moon-glade background oriented Schlieren and surface temperature measurements using infrared thermography. Also, numerical simulations of the flow development are performed and a new similarity solution for the steady state in a laterally unbounded domain is constructed, which takes into account the pressure gradient. The results are shown to be in good agreement with experimental data. The obtained dependencies of the maximal velocity, boundary layer thickness, local and total Nusselt numbers on the Rayleigh number are consistent with literature data obtained for the non-uniformly heated bottom case, which demonstrates universal properties of horizontal convection.

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Mobility of free surface in different liquids and its influence on water striders locomotion

Cited by 14 publications

References 25 publications

Dynamics of Microcystis surface scum formation under different wind conditions: the role of hydrodynamic processes at the air-water interface

Dynamics of Microcystis surface scum formation under different wind conditions: the role of hydrodynamic processes at the air-water interface

Patterns of load distribution among the legs in small water striders during standing and striding

Horizontal convective flow from a line heat source located at the liquid–gas interface in presence of surface film

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