Case design and flow resistance in high-alpine caddisfly larvae (Insecta, Trichoptera).

Unlabelled: For evaluating hydraulic stress reduction strategies of caddisfly larvae, our study has three goals. First, creating a database on Reynolds numbers () and drag coefficients valid for Limnephilidae larvae with cylindrical mineral cases. Second, evaluating the effects of submerged weight and biometry in cases with comparable length/width ratios.

Comparing head muscles among Drusinae clades (Insecta: Trichoptera) reveals high congruence despite strong contrasts in head shape.

The subfamily Drusinae (Limnephilidae, Trichoptera) comprises a range of species exhibiting differently shaped head capsules in their larval stages. These correspond to evolutionary lineages pursuing different larval feeding ecologies, each of which uses a different hydraulic niche: scraping grazers and omnivorous shredders sharing rounded head capsules and filtering carnivores with indented and corrugated head capsules. In this study, we assess whether changes in head capsule morphology are reflected by changes in internal anatomy of Drusinae heads.

External and internal head anatomy of (Trichoptera, Limnephilidae).

External And Internal Head Anatomy Of Drusus Monticola Trichoptera Limnephilidae: Caddisflies have evolved to a staggering diversity, and their larvae inhabit a wide range of different habitats. Also, the larvae differ in their (feeding) ecology, and hydrological niche preference. Consequently, groups differ in their external morphology, a fact that allows to identify many taxa to species-level in the larval stage.

Hydraulic niche utilization by larvae of the three Drusinae clades (Insecta: Trichoptera).

Hydraulic niche descriptors of final instar larvae of nine species (Trichoptera) were studied in small, spring-fed, first-order headwaters located in the Mühlviertel (Upper Austria), Koralpe (Carinthia, Austria), and in the Austrian and Italian Alps. The species investigated covered all three clades of Drusinae: the shredder clade (, ), the grazer clade (, , , ), and the filtering carnivore clade (, , ). Flow velocity was measured at front center of 68 larvae, head upstream, on the top of mineral substrate particles at water depths of 10-30 mm, using a tripod-stabilized Micro propeller meter (propeller diameter = 10 mm).

Hydraulic stress parameters of a cased caddis larva () using spatio-temporally filtered velocity measurements.

By studying hydraulic stress parameters of larvae of the cased caddisfly (Pictet, 1834) in a tributary of the Schwarze Sulm (Carinthia, Austria), we aimed on (1) detecting the flow properties of the spatio-temporally filtered velocity measurements taken, and (2) on defining the hydraulic niche of this caddisfly larva. For this, we took 31 measurement series lasting 30 to 300 s, yielding 2176 single velocity measurements. The probability density functions of the 31 data series were Gaussian or sub-Gaussian, and the mean recurrent interval between velocity maxima within a data series was only 15.

Lagrangian chaos in steady three-dimensional lid-driven cavity flow.

Steady three-dimensional flows in lid-driven cavities are investigated numerically using a high-order spectral-element solver for the incompressible Navier-Stokes equations. The focus is placed on critical points in the flow field, critical limit cycles, their heteroclinic connections, and on the existence, shape, and dependence on the Reynolds number of Kolmogorov-Arnold-Moser (KAM) tori. In finite-length cuboidal cavities at small Reynolds numbers, a thin layer of chaotic streamlines covers all walls.

A new Drusinae species from the western Alps with comments on the subfamily and an updated key to filtering carnivore larvae of Drusinae species (Insecta: Trichoptera: Limnephilidae).

A new Drusinae species, sp. nov., of the Species Complex, is described based on a male and associated larvae.

Project overview: Intricate bodies in the boundary layer - bridging fluid mechanics, morphology and ecology in larval Drusinae (Insecta: Trichoptera).

This paper summarizes the layout, the three work packages and the intended outcome of the project 'Intricate bodies in the boundary layer P 31258-B29', funded by the Austrian Science Fund (FWF ; project start: October 2018).

Topology of hydrothermal waves in liquid bridges and dissipative structures of transported particles.

High-resolution three-dimensional numerical simulations are carried out for hydrothermal waves in a thermocapillary liquid bridge with Prandtl number Pr=4 and length-to-radius aspect ratio Γ=0.66. The flow topology is analyzed using Poincaré sections in a frame of reference co-rotating with the phase velocity of the wave.

Airflow elicits a spider's jump towards airborne prey. II. Flow characteristics guiding behaviour.

When hungry, the wandering spider Cupiennius salei is frequently seen to catch flying insect prey. The success of its remarkable prey-capture jump from its sitting plant into the air obviously depends on proper timing and sensory guidance. In this study, it is shown that particular features of the airflow generated by the insect suffice to guide the spider.

Particle-accumulation structures in periodic free-surface flows: inertia versus surface collisions.

The role of particle inertia and particle-free-surface collisions in periodic free-surface flows is evaluated in the framework of an analytical flow model for a thermocapillary liquid bridge. Inertia and particle-free-surface collisions lead to particle accumulation, but on different time scales, and can lead to different accumulation patterns. A comparison with experimental results provides strong evidence that the experimentally observed accumulation patterns are due to particle-free-surface collisions.

Airflow elicits a spider's jump towards airborne prey. I. Airflow around a flying blowfly.

The hunting spider Cupiennius salei uses airflow generated by flying insects for the guidance of its prey-capture jump. We investigated the velocity field of the airflow generated by a freely flying blowfly close to the flow sensors on the spider's legs. It shows three characteristic phases (I-III).