Self-turbulization

Sivashinsky, G. I. 1979. On self-turbulization of a laminar flame. Acta Astronautica. 6 569-591. 

In the early investigations of hydrodynamic instability [9], [190], it was presumed that the instability evolves to a chaotic state characteristic of turbulence. Thus self-turbulization of premixed flames was attributed to hydrodynamic instability (analogous, in a sense, to the development of turbulence in shear flows). This viewpoint must be revised if the instability evolves to stable nonplanar structures, as suggested above. From numerical experiments with equations describing the self-evolution of flame surfaces in the limit of small values of the density change across the flame, it has been inferred [152], [198]-[200] that the hydrodynamic instability evolves... 

Derivation of basic equations. Acta Astronautica 4, 1177 Sivashinsky, G. I. (1979) On self-turbulization of a laminar flame. Acta Astronautica 6, 569 Stewartson, K., Stuart, J. T. (1971) A non-linear instability theory for a wave system in plane Poiseuille flow. J. Fluid Mech. 48, 529... 

The first analysis of the wrinkled flame structure was carried out by Barenblatt, Zeldovich and Istratov (1962) but in the diffusive-thermal model where the gas expansion effects i) and ii) are neglected. This model was extensively used these ten last years to culminate in the derivation by G. Sivashinsky (1977) of a non linear differential equation for the flame motion describing a self turbulizing behavior of the cellular structures (Michelson 6e Sivashinsky 1977). The main interest of this model is to provide us with a simple framework for studying systematically all the d3mamical effects that can possibely be produced by the diffusion of heat and mass. The asymptotic technique applied to solve this model in the limit of large values of the Zeldovich number is presented in the paper of Jou 1 in 6e Clavin (1979)... 

Since there are no dead spaces in a SHE, the helical flow pattern combines to entrain any solids and create high turbulence creating a self-cleaning flow passage. 

A calibration facility must produce the desired velocity range for the meter to be calibrated. The air temperature should be kept constant over the test to ensure constant density. For thermal anemometers, velocity calibration only is not sufficient. They should also be checked for temperature compensation. In the case of omnidirectional probes, sensitivity to flow direction should be tested. In the case of low-speed (thermal) anemometers, their self-convection error should be measured, and, for instruments measuring flow fluctuation (turbulence), dynamic characteristics testing should be carried out as well. ... 

The preceding section described the state of transition expected in a deflagration process when the mixture in front of the flame is sufficiently preconditioned by a combination of compression effects and local quenching by turbulent mixing. However, additional factors determine whether the onset of detonation can actually occur and whether the onset of detonation will be followed by a self-sustaining detonation wave. 

Different investigations of the possible connection between rotation and the Li dip have appeared in the literature. Most relied on highly simplified descriptions of the rotation-induced mixing processes. In the MC model of Tassoul Tassoul (1982) used by Charbonneau Michaud (1988), the feed-back effect due to angular momentum (hereafter AM) transport as well as the induced turbulence were ignored. Following Zahn (1992), Charbonnel et al. (1992, 1994) considered the interaction between MC and turbulence induced by rotation, but the transport of AM was not treated self-consistently. 

We have now to go one step further and to build stellar evolution models where the transport of angular momentum will be followed self-consistently under the action of meridional circulation, shear turbulence, and internal gravity waves. In this path some important aspects still need to be clarified Can we better describe the excitation mechanisms and evaluate in a more reliable way the quantitative properties of the wave spectra What is the direct contribution of 1GW to the transport of chemicals, especially in the dynamical shear layer produced just below the convective envelope by the wave-mean flow interaction What is the influence of the Coriolis force on IGW How do 1GW interact with a magnetic field Work is in progress in this direction. 

Another approach is increasing throughput via a monolith analytical column. Vintiloiu et al. (2005) used a self-made RAM online SPE under turbulent flow conditions to measure rofecoxib, a cyclooxygenase-2 inhibitor, in rat plasma. They constructed a cartridge (0.76 x 50 mm) packed with LiChrosphere 60 RP-18 ADS particles (40 to 63 /an, Merck KgaA). The analytical column was a Chromolith Speed ROD (RP-18, 50 x 4.6 mm, Merck KgaA). The injection volume was... 

A second aim has been to make the book more nearly self-contained and to this end a substantial introductory chapter has been written. In addition to the material provided in the first edition, the principles of continuity, momentum of a flowing fluid, and stresses in fluids are discussed. There is also an elementary treatment of turbulence. 

Dahm, W. J. A. and P. E. Dimotakis (1990). Mixing at large Schmidt number in the self-similar far field of turbulent jets. Journal of Fluid Mechanics 217, 299-330. 

Yeung, P. K. (1994). Spectral transport of self-similar passive scalar fields in isotropic turbulence. Physics of Fluids 6, 2245-2247. 

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