Turbulence cascade

IIIC, D) Vidal, C., Bachelart, S., Rossi, A. Bifurcations in Turbulent Cascades in the Belousov-... 

Before the relevant turbulent shear can be assessed, it is necessary to know the scale of interest and understand its relevance to the turbulent cascade (transfer of energy from large to small scales). The Kolmogoroff microscale Lt is given by ... 

Systems that are exposed to excessive turbulence of anaerobic wastewater and a potential increased release of hydrogen sulfide. Systems with a risk for increased turbulence are inlet structures, drops, cascades, sharp bends and inverted siphons. As an example, changes in the flow regime from a pressure pipe into a gravity sewer may give rise to the release of hydrogen sulfide. Corrosion of the sewer pipe wall is often pronounced near the daily water... 

The turbulent energy, extracted from the mean flow, passes through the energy cascade and is ultimately converted into internal energy by viscous dissipation. 

At high Reynolds numbers, we can again expect the small scales of the scalar field to be nearly isotropic. In the classical picture of turbulent mixing, one speaks of scalar eddies produced at large scales, with a distinct directional orientation, that lose their directional preference as they cascade down to small scales where they are dissipated by molecular diffusion. 

Meneveau, C. and J. Katz (2000). On the Lagrangian nature of the turbulence energy cascade. 

Laminar Turbulence Smoke Travels away from Critical Work Surface Cascade Airflow ... 

The diffusion in a velocity field with a wide velocity spectrum supposedly describing turbulence is considered in the spirit of cascade-renormalization ideas. For the latter case of isotropic turbulence, we construct an ordinary differential equation for the turbulent diffusion coefficient. 

We consider that the cascade occurs at equal intervals on the logarithmic scale of the quantity A. We replace the difference equation by a differential one. In doing so, we introduce an empirical coefficient, a which accounts for the fact that, in heat transfer in a given direction, only the component of the turbulent velocity in this direction takes part. Finally we propose the equation (omitting the overbar in A)... 

Thus, in this paper we have obtained an exact solution of the diffusion equation for one-dimensional motion of an incompressible fluid, and determined the effective diffusion coefficient. We have constructed an approximate theory of turbulent diffusion as a cascade process of motion interaction on different scales. We have obtained an expression for the turbulent diffusion coefficient with the correct transformation properties under time reversal. 

These shortcomings prevail also in Shelf cascade classifier [6], where instead of pipes, inclined shelves are mounted on the inner walls of a vertical vessel (Fig. 2b). Strong turbulence prevailing under the shelves cause high pressure drops (of up to 4-5 kPa) and high energy consumption of these devices. 

The collection of eddies that appear for identical reasons is called eddy group in this section. When the cascade process of turbulent kinetic energy transfer is considered, it can be understood that the smallest eddy group, that is, the basic eddy group, is determined naturally for an individual fluid, according to its property of viscosity. 

Complicated Reactions and Flow. The ideal turbulence model must deal with multiscale effects within the subgrid model. If there is a delay as velocity cascades to the short wavelength end of the spectrum due to chemical kinetics or buoyancy, for example, the model must be capable of representing this. Otherwise bursts and intermittency phenomena cannot be calculated. 

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