scholarly journals Small-scale shear effects on heterocystous cyanobacteria

2002 ◽  
Vol 47 (1) ◽  
pp. 108-119 ◽  
Author(s):  
Pia H. Moisander ◽  
James L. Hench ◽  
Kaisa Kononen ◽  
Hans W. Paerl
Keyword(s):  
Small Scale ◽  
Heterocystous Cyanobacteria ◽  
Shear Effects ◽  
Scale Shear

Characteristics of small-scale shear layers in a temporally evolving turbulent planar jet

2021 ◽  
Vol 920 ◽  
Author(s):  
Masato Hayashi ◽  
Tomoaki Watanabe ◽  
Koji Nagata
Keyword(s):  
Shear Layers ◽  
Small Scale ◽  
Planar Jet ◽  
Scale Shear

Abstract

Study of turbulent structure with hot wires smaller than the viscous length

1984 ◽  
Vol 142 ◽  
pp. 121-149 ◽  
Author(s):  
William W. Willmarth ◽  
Lalit K. Sharma
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Velocity Gradient ◽  
Shear Layers ◽  
Small Scale ◽  
Wall Region ◽  
Burst Frequency ◽  
Velocity Fluctuations ◽  
Hot Wires ◽  
Scale Shear

The small-scale structure of the streamwise velocity fluctuations in the wall region of a turbulent boundary layer is examined in a new wind-tunnel facility using hot-wires smaller than any previously constructed (typical dimensions: l = 25 μm, d = 0.5 μm). In the boundary layer in which the measurements were made, the ratio of the hot-wire length to the viscous length is 0.3. The turbulent intensity measured with the small hot wires is larger than that measured with longer wires owing to the better spatial resolution of the small wires. The velocity fluctuations measured by the small hot wires are also analysed to determine the burst frequency at two Reynolds numbers and at various distances from the wall. The dimensionless burst frequency does not depend on the Reynolds number when scaled with wall parameters. However, it increases with Reynolds number when scaled with outer variables. Velocity fluctuations measured by two hot wires, less than two viscous lengths apart, are analysed to reveal the small-scale features present during a burst and in the absence of a burst. The main conclusions are: (1) intermittent small-scale shear layers occur most frequently when bursts are present, less frequently just after a burst, and even less frequently just before a burst; and (2) on occasion the velocity gradient of the small-scale shear layers is as large as the mean-velocity gradient at the wall.

scholarly journals Test Arrangement of Small-scale Shear Tests of Composite Slabs

2016 ◽  
Vol 161 ◽  
pp. 716-721 ◽  
Author(s):  
Josef Holomek ◽  
Miroslav Bajera ◽  
Martin Vilda
Keyword(s):  
Small Scale ◽  
Shear Tests ◽  
Composite Slabs ◽  
Scale Shear

scholarly journals Enhancement of Small-scale Turbulent Dynamo by Large-scale Shear

2017 ◽  
Vol 850 (1) ◽  
pp. L8 ◽  
Author(s):  
Nishant K. Singh ◽  
Igor Rogachevskii ◽  
Axel Brandenburg
Keyword(s):  
Large Scale ◽  
Small Scale ◽  
Turbulent Dynamo ◽  
Scale Shear

Effect of small-scale shear on grazing and growth of the dinoflagellate Pfiesteria piscicida

Harmful Algae ◽  
2006 ◽  
Vol 5 (4) ◽  
pp. 407-418 ◽  
Author(s):  
Diane K. Stoecker ◽  
Amy Long ◽  
Steven E. Suttles ◽  
Lawrence P. Sanford
Keyword(s):  
Small Scale ◽  
Pfiesteria Piscicida ◽  
Scale Shear

Small-scale shear connectors in HSC/UHPC

2016 ◽  
Author(s):  
Martin Classen ◽  
Martin Herbrand ◽  
Alexander Stark ◽  
Josef Hegger
Keyword(s):  
Small Scale ◽  
Shear Connectors ◽  
Scale Shear

Shear Tests of Composite Slabs, Experimental and Numerical Investigation

2014 ◽  
Vol 923 ◽  
pp. 217-220 ◽  
Author(s):  
Josef Holomek ◽  
Miroslav Bajer ◽  
Jan Barnat ◽  
Martin Vild
Keyword(s):  
Large Scale ◽  
Small Scale ◽  
Concrete Slabs ◽  
Shear Tests ◽  
Composite Action ◽  
Permanent Formwork ◽  
Composite Slabs ◽  
New Type ◽  
Large Scale Tests ◽  
Scale Shear

Composite slab is being used for horizontal structures. The sheeting can serve as a permanent formwork and no additional reinforcement can be required. The slabs are then fast and easy assemble construction which can be effectively used in reconstructions. One of the meanings to assure composite action of composite steel-concrete slabs is prepressed embossments. Its main disadvantage is that the design of a new type of sheeting requires expensive and time consuming large-scale laboratory testing which hamper its widespread commercial usage. Small-scale shear tests present a less expensive alternative to the large-scale tests but its results cannot be simply used for the design of the whole slab. The results from small-scale tests with different options are compared in this paper. Also a possibility of contribution of FE simulation results to the small-scale tests usage is investigated.

scholarly journals PIV Measurements in the Atmospheric Boundary Layer within and above a Mature Corn Canopy. Part II: Quadrant-Hole Analysis

2007 ◽  
Vol 64 (8) ◽  
pp. 2825-2838 ◽  
Author(s):  
W. Zhu ◽  
R. van Hout ◽  
J. Katz
Keyword(s):  
Dissipation Rate ◽  
Large Scale ◽  
Reynolds Shear Stress ◽  
Small Scale ◽  
Shear Stresses ◽  
Reynolds Stresses ◽  
Piv Measurements ◽  
Dissipation Rates ◽  
Scale Shear ◽  
Corn Canopy

Quadrant-hole (Q-H) analysis is applied to PIV data acquired just within and above a mature corn canopy. The Reynolds shear stresses, transverse components of vorticity, as well as turbulence production and cascading part of dissipation rates are conditionally sampled in each quadrant, based on stress and vorticity magnitudes. The stresses are representative of large-scale events, while the vorticity is dominated by small-scale shear. Dissipation rates (cascading energy fluxes) are evaluated by fitting −5/3 slope lines to the conditionally sampled and averaged spatial energy spectra, while the Reynolds stresses, vorticity, and production rates are calculated directly from the spatial distributions of two velocity components. The results demonstrate that sweep (quadrant 4) and ejection (quadrant 2) events are the dominant contributors to the Reynolds shear stress, consistent with previous observations. The analysis also shows a strong correlation between magnitudes of dissipation rate and vorticity. The dissipation rates and vorticity magnitudes are higher in quadrants 1 and 4, that is, when the horizontal component of the fluctuating velocity is positive, peaking in quadrant 1. Both are weakly correlated with the Reynolds stresses except for rare quadrant 1 events. However, the more frequently occurring quadrant 4 events are the largest contributors to the dissipation rate. The production rate inherently increases with increasing stress magnitude, but lacks correlation with vorticity. Quadrants 2 and 4 contribute the most to production. However, the contribution of quadrant 1 events to negative production should not be ignored above canopy. The results show a strong disconnection between small-scale- and large-scale-dominated phenomena.

scholarly journals Localization effect on AMS fabric revealed by microstructural evidence across small-scale shear zone in marble

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
V. K. Kusbach ◽  
M. Machek ◽  
Z. Roxerová ◽  
M. Racek ◽  
P. F. Silva
Keyword(s):  
Shear Zone ◽  
Magnetic Fabric ◽  
Small Scale ◽  
Angular Deviation ◽  
Localized Deformation ◽  
Fine Grained ◽  
Localization Of Deformation ◽  
Strain Relationship ◽  
Rock Microstructure ◽  
Scale Shear

AbstractAnisotropy of magnetic susceptibility (AMS) is regularly applied as a tool to infer structural analysis of deformation and flow in rocks, particularly, with low anisotropy. AMS integrates the magnetic signature of crystallographic and shape preferred orientation of all mineral grains present in the rock microstructure. Those preferred orientations result from multiple processes affecting the rock during its evolution, therefore the desirable AMS-strain relationship is not straightforward. Here we show that due to localization of deformation, AMS is indirectly dependent on the magnitude and character of deformation. In order to decipher the AMS-strain relationship, AMS studies should be accompanied by microstructural analyses combined with numerical modelling of magnetic fabric. A small-scale shear zone produced by single deformation event was studied. The resultant AMS fabric is “inverse” due to the presence of Fe-dolomite and controlled by calcite and dolomite crystallographic preferred orientations. The localized deformation resulted in the angular deviation between macroscopic and magnetic fabric in the shear zone, systematically increasing with increasing strain. This is a result of the presence of microstructural subfabrics of coarse porphyroclasts and fine-grained recrystallized matrix produced by localization.The localization of deformation is a multiscale and widespread process that should be considered whenever interpreting AMS in deformed rocks and regions.

Sign in / Sign up

Export Citation Format

Share Document