Eddy structures

The above discussion holds for dispersion by atmospheric turbulence. In addition, a momentum release of fuel sometimes generates its own turbulence, e.g., when a fuel is released at high pressure in the form of a high-intensity turbulent jet. Fuel mixes rapidly with air within the jet. Large-scale eddy structures near the edges of the jet entrain surrounding air. Compositional homogeneity, in such cases, can be expected only downstream toward the jet s centerline. 

Intense mixing of burned and unbumed components within large, coherent, turbulent, eddy structures of a jet may lead to local conditions that may induce the SWACER mechanism and trigger detonation. 

Chigiefl211 found that turbulence in a liquid jet has important disturbing influences throughout the liquid flow. At the liquid surface, turbulent velocity fluctuations directly cause protuberances and roughness that result in direct stripping by surrounding air flow. Large eddy structures in the air flow penetrate into the liquid and... 

Bhat, G. S., and R. Narasimha. 1996. A volumetric ally heated jet Large-eddy structure and entraiirment characteristics. J. Fluid Mechanics 325 303-30. 

The first group of models ( eddy models) assumes that the liquid renewal is due to small-scale eddies of the turbulent field. These models are based on idealized eddy structures of turbulence in the bubble vicinity. Lamont and Scott [1] have assumed that the small scales of turbulent motion, which extend from the smallest viscous motions to the iner-... 

V. Linek, M. Fujasova, M. Kordae, T. Moucha, Gas-liquid mass transfer coefficient in stirred tank interpreted through models of idealized eddy structure of turbulence in the bubble vicinity, Chem. Eng. Proc. (in press). 

Dr. John Finnigan from Australian Commonwealth Scientific and Industrial Research Organization (CSIRO), Australia in his chapter extends his analysis of the eddy structure of canopy winds to include the effects of complex topography. He shows that there are special features of airflow through forests and over hills that significantly affect the weather and the ecology in these very common situations. 

Prof. Julian Hunt (University College London) introduces a classification of the types of turbulent flow through canopies of different kinds of geometry and length scale. He shows how, by integrating recently developed concepts by many authors, a more comprehensive understanding of eddy structure and turbulence statistics is now emerging. In the atmosphere where canopies may extend over tens of kilometres in... 

An alternative point of view is that vorticity accumulates at the rear of the body, which leads to a large recirculating eddy structure, and as a consequence, the flow in the vicinity of the body surface is forced to detach from the surface. This is quite a different mechanism from the first one because it assumes that the primary process leading to separation is the production and accumulation of vorticity rather than the local dynamics within the boundary layer.25 However, viscosity still plays a critical role for a solid body in the production of vorticity. In fact, for any finite Reynolds number, there is probably some element of truth in both explanations. Furthermore, it is unlikely that experimental evidence (or evidence based on numerical solutions of the complete Navier Stokes equations) will be able to distinguish between these ideas, because such evidence for steady flows will inevitably be limited to moderate Reynolds numbers. 

Turbulence occurs in any sufficiently rapid flow when the fluid inertia exceeds its molecular friction. It is the typical flow regime when suspensions of relatively low viscosity are dispersed—e.g. by stirring or in nozzles. Turbulent flow is characterised by multiscale eddy structures that erratically move through the flow field and cause local fluctuations in velocity and pressure. The velocity fluctuations can be quantified by the effective velocity difference Am over a distance Ar (Kolmogorov 1958). For the inertial subrange of microturbulence, it amounts to ... 

H.Li and T.Nozaki, Wavelet Analysis for the Plane Turbulence Jet (Analysis of large eddy structure), JSME International Journal Fluids and Thermal Engineering, Vol.38, No.4 pp525-531 (1995)... 

Effects of polymer stresses on eddy structures in drag-reduced turbulent channel flow. J. fluid Mech., 584, 281-299. 

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