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

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 The electromotive force in multi-scale flows at high magnetic Reynolds number

2015 ◽  
Vol 81 (6) ◽  
Author(s):  
Steven M. Tobias ◽  
Fausto Cattaneo
Keyword(s):  
Reynolds Number ◽  
Electromotive Force ◽  
Large Scale ◽  
Magnetic Reynolds Number ◽  
Small Scale ◽  
Dynamo Theory ◽  
Multi Scale ◽  
The Mean ◽  
Scale Shear

Recent advances in dynamo theory have been made by examining the competition between small- and large-scale dynamos at high magnetic Reynolds number $\mathit{Rm}$. Small-scale dynamos rely on the presence of chaotic stretching whilst the generation of large-scale fields occurs in flows lacking reflectional symmetry via a systematic electromotive force (EMF). In this paper we discuss how the statistics of the EMF (at high $\mathit{Rm}$) depend on the properties of the multi-scale velocity that is generating it. In particular, we determine that different scales of flow have different contributions to the statistics of the EMF, with smaller scales contributing to the mean without increasing the variance. Moreover, we determine when scales in such a flow act independently in their contribution to the EMF. We further examine the role of large-scale shear in modifying the EMF. We conjecture that the distribution of the EMF, and not simply the mean, largely determines the dominant scale of the magnetic field generated by the flow.

scholarly journals Elasticity of tangled magnetic fields

2020 ◽  
Vol 86 (5) ◽  
Author(s):  
D. N. Hosking ◽  
A. A. Schekochihin ◽  
S. A. Balbus
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Large Scale ◽  
Mean Field ◽  
Field Configuration ◽  
Small Scale ◽  
Elastic Strings ◽  
Field Formalism ◽  
Magnetoelastic Waves ◽  
Scale Shear

The fundamental difference between incompressible ideal magnetohydrodynamics and the dynamics of a non-conducting fluid is that magnetic fields exert a tension force that opposes their bending; magnetic fields behave like elastic strings threading the fluid. It is natural, therefore, to expect that a magnetic field tangled at small length scales should resist a large-scale shear in an elastic way, much as a ball of tangled elastic strings responds elastically to an impulse. Furthermore, a tangled field should support the propagation of ‘magnetoelastic waves’, the isotropic analogue of Alfvén waves on a straight magnetic field. Here, we study magnetoelasticity in the idealised context of an equilibrium tangled field configuration. In contrast to previous treatments, we explicitly account for intermittency of the Maxwell stress, and show that this intermittency necessarily decreases the frequency of magnetoelastic waves in a stable field configuration. We develop a mean-field formalism to describe magnetoelastic behaviour, retaining leading-order corrections due to the coupling of large- and small-scale motions, and solve the initial-value problem for viscous fluids subjected to a large-scale shear, showing that the development of small-scale motions results in anomalous viscous damping of large-scale waves. Finally, we test these analytic predictions using numerical simulations of standing waves on tangled, linear force-free magnetic-field equilibria.

scholarly journals Generation of large-scale vorticity in rotating stratified turbulence with inhomogeneous helicity: mean-field theory

2018 ◽  
Vol 84 (3) ◽  
Author(s):  
N. Kleeorin ◽  
I. Rogachevskii
Keyword(s):  
Field Theory ◽  
Reynolds Stress ◽  
Large Scale ◽  
Mean Field Theory ◽  
Mean Field ◽  
Combined Effect ◽  
Small Scale ◽  
Stratified Turbulence ◽  
Developed Turbulence ◽  
Scale Shear

We discuss a mean-field theory of the generation of large-scale vorticity in a rotating density stratified developed turbulence with inhomogeneous kinetic helicity. We show that the large-scale non-uniform flow is produced due to either a combined action of a density stratified rotating turbulence and uniform kinetic helicity or a combined effect of a rotating incompressible turbulence and inhomogeneous kinetic helicity. These effects result in the formation of a large-scale shear, and in turn its interaction with the small-scale turbulence causes an excitation of the large-scale instability (known as a vorticity dynamo) due to a combined effect of the large-scale shear and Reynolds stress-induced generation of the mean vorticity. The latter is due to the effect of large-scale shear on the Reynolds stress. A fast rotation suppresses this large-scale instability.

Small-Scale Science to Large-Scale Profession

2000 ◽  
Vol 45 (4) ◽  
pp. 396-398
Author(s):  
Roger Smith
Keyword(s):  
Large Scale ◽  
Small Scale

Development of Physics Learning Module Based on Guided Inquiry with Light Wave Material in Class XI of Senior High School

2020 ◽  
Vol 1 (1) ◽  
pp. 1-10
Author(s):  
Evi Rahmawati ◽  
Irnin Agustina Dwi Astuti ◽  
N Nurhayati
Keyword(s):  
Large Scale ◽  
Learning Strategy ◽  
Student Response ◽  
Average Score ◽  
Small Scale ◽  
Design Development ◽  
Teacher Response ◽  
Student Responses ◽  
Analysis Design ◽  
Scientific Skills

IPA Integrated is a place for students to study themselves and the surrounding environment applied in daily life. Integrated IPA Learning provides a direct experience to students through the use and development of scientific skills and attitudes. The importance of integrated IPA requires to pack learning well, integrated IPA integration with the preparation of modules combined with learning strategy can maximize the learning process in school. In SMP 209 Jakarta, the value of the integrated IPA is obtained from 34 students there are 10 students completed and 24 students are not complete because they get the value below the KKM of 68. This research is a development study with the development model of ADDIE (Analysis, Design, Development, Implementation, and Evaluation). The use of KPS-based integrated IPA modules (Science Process sSkills) on the theme of rainbow phenomenon obtained by media expert validation results with an average score of 84.38%, average material expert 82.18%, average linguist 75.37%. So the average of all aspects obtained by 80.55% is worth using and tested to students. The results of the teacher response obtained 88.69% value with excellent criteria. Student responses on a small scale acquired an average score of 85.19% with highly agreed criteria and on the large-scale student response gained a yield of 86.44% with very agreed criteria. So the module can be concluded receiving a good response by the teacher and students.

Planetary gentrification and urban (re)development

2019 ◽  
Vol 61 (1) ◽  
pp. 5-13 ◽  
Author(s):  
Loretta Lees
Keyword(s):  
Low Income ◽  
Policy Making ◽  
Large Scale ◽  
Urban Redevelopment ◽  
Urban Transformation ◽  
Small Scale ◽  
Income Groups ◽  
Low Income Groups

Abstract Gentrification is no-longer, if it ever was, a small scale process of urban transformation. Gentrification globally is more often practised as large scale urban redevelopment. It is state-led or state-induced. The results are clear – the displacement and disenfranchisement of low income groups in favour of wealthier in-movers. So, why has gentrification come to dominate policy making worldwide and what can be done about it?

AGRICULTURAL PRODUCTION OF CA DONG PEOPLE IN RESETTLEMENT AREA OF TRANH RIVER HYDROPOWER NUMBER 2: CURRENT SITUATION AND IMPACT FACTORS

2020 ◽  
Vol 9 (2) ◽  
Author(s):  
Bùi Thị Bích Lan
Keyword(s):  
Social Relations ◽  
Agricultural Production ◽  
Large Scale ◽  
Transition Process ◽  
Impact Factors ◽  
Small Scale ◽  
Scale Production ◽  
Technical Application ◽  
Production Models ◽  
Role Of The State

In Vietnam, the construction of hydropower projects has contributed significantly in the cause of industrialization and modernization of the country. The place where hydropower projects are built is mostly inhabited by ethnic minorities - communities that rely primarily on land, a very important source of livelihood security. In the context of the lack of common productive land in resettlement areas, the orientation for agricultural production is to promote indigenous knowledge combined with increasing scientific and technical application; shifting from small-scale production practices to large-scale commodity production. However, the research results of this article show that many obstacles in the transition process are being posed such as limitations on natural resources, traditional production thinking or the suitability and effectiveness of scientific - technical application models. When agricultural production does not ensure food security, a number of implications for people’s lives are increasingly evident, such as poverty, preserving cultural identity, social relations and resource protection. Since then, it has set the role of the State in researching and building appropriate agricultural production models to exploit local strengths and ensure sustainability.

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