Search results: Found 3

Listing 1 - 3 of 3
Sort by
Construire des mondes

Author:
ISBN: 9782853995962 9782821885493 Year: Language: French
Publisher: Presses universitaires de Provence
Added to DOAB on : 2017-11-21 16:19:30
License: OpenEdition licence for Books

Loading...
Export citation

Choose an application

Abstract

L'espace méditerranéen n'a pas seulement été « inventé » depuis les trois derniers siècles : il a été aussi construit - ou reconstruit - dans le cadre de mutations qui ont affecté le politique, l'économie, le social et le culturel et dans lesquelles les élites ont toujours joué un rôle moteur. Cet ouvrage poursuit deux objectifs. Le premier consiste à prendre en considération l'ensemble du processus avec ses différences de formes et de niveaux. Le deuxième porte sur les stratégies des acteur...

La consistance du social

Author:
ISBN: 9782753500563 9782753537309 Year: Language: French
Publisher: Presses universitaires de Rennes
Added to DOAB on : 2017-03-22 17:18:59
License: OpenEdition licence for Books

Loading...
Export citation

Choose an application

Abstract

Cet ouvrage interroge la manière dont se tissent les liens sociaux entre les individus, de quoi sont faites nos vies en tant qu'acteurs sociaux. Il envisage également comment les sociologues peuvent envisager d'en rendre compte.

Shallow turbulent wake flows: momentum and mass transfer due to large-scale coherent vortical structures

Author:
Book Series: Dissertationsreihe am Institut für Hydromechanik der Universität Karlsruhe (TH) ISSN: 14394111 ISBN: 3937300635 Year: Volume: 2005,2 Pages: XXVI, 398 p. DOI: 10.5445/KSP/1000003453 Language: ENGLISH
Publisher: KIT Scientific Publishing
Subject: General and Civil Engineering
Added to DOAB on : 2019-07-30 20:01:59
License:

Loading...
Export citation

Choose an application

Abstract

Shallow turbulent wake flows are generated by large obstacles - like islands or headlands - introduced to shallow turbulent open-channel flows. Large-scale quasi two-dimensional vortices may shed off from an obstacle, and advect downstream in a vertical shear flow with predominantly small-scale turbulence induced by bottom friction. Experimental, analytical, and numerical techniques are employed in the present study to characterize the mean flow and turbulence properties of shallow wakes; mechanisms of generation and decay of large-scale vortical structures are clarified, as is their influence on momentum and mass transport in shallow wakes; the global and local stability of shallow wakes is analyzed and evidenced from experimental data. Part I of this work covers non-intrusive optical measurement techniques especially adapted to investigate shallow shear flows. Flow velocities and mass concentrations are obtained (i) point-wise with high spatiotemporal resolution using a combinded LDV-LIF system, and (ii) field-wise using near-surface PIV and depth-averaged PCA systems with a coupling by phase-resolved averaging. Improved algorithms for the evaluation of mass concentrations are based on hydro-optical models of the underlying fluorescence and light attenuation processes. Part II addresses the time-mean description of shallow wake flows. The stochastic description of the turbulence fields displays a characteristic spectral distribution both of kinetic energy and of mass variance, which is partially consistent with the theory of unbounded 2D turbulence at large scales, and with the theory of homogeneous 3D turbulence at small scales. An integral wake model including the effect of bottom friction is derived analytically, and is validated by experimental data. The time-mean distributions of flow velocities and of mass concentration allow to identify wake near fields and far fields with specific asymptotic wake developments. Wake stability classes are associated with local stability regions suggested by linear stability analyses. Part III elaborates the structure and dynamics of quasi-periodic wake flows and the significance of large-scale eddies. This involves a structure identification scheme to educe individual vortices, and a phase-resolved averaging procedure to decompose the flow fields into large-scale coherent and small-scale turbulent parts. A Numerical Particle Tracking technique is employed to model the mass transport and to elucidate different diffusion and dispersion effects.

Listing 1 - 3 of 3
Sort by