Instabilities double diffusion

Thermal SN explosion mechanism was proposed by Colgate and White [32], In this picture, part of the neutrino flux liberated in the core collapse is deposited to the stellar mantle to make it unbound ( 1051 ergs is needed). Specific mechanisms include neutrino-driven fluid instabilities, for example convection both above neutrinosphere and inside the proto-NS. Neutrino-driven convection, however, may not be as important as thought before, as follows from recent detailed 2D studies of convection [24], Instead, other fluid instabilities such as newly found double-diffusive instability (the so-called lepto-entropy fingers ) [23], may effectively increase neutrino luminosity to help successful explosion. Note here that process ve -I u(, e1 I e —>7 + 7... 

We describe cases when FP is expected to be observed. The first case is the polymerization of crosslinking monomers (thermosets). The second group of monomers form polymers that are insoluble in the monomer. Good examples are acrylic and methanylic adds. Insoluble polymer particles adhere to each other during thdr formation and stick to the reactor or test tube walls, forming a mechanically stable phase and discernible polymer-monomer interface. Nonetheless, Rayleigh-Taylor and double-diffusive instabilities, which we will discuss... 

When there is no free surface, this range is substantially reduced. Nevertheless, we still observe the formation of structures (37). Since we can no longer invoke an interfacial instability in this case, since a B nard instability (due to a vertical gradient of temperature or composition) appears less probable, it is thus wise to envisage (38) the intervention of a double diffusion process (39). In any case, we thus enter the domain of conjecture. 

The resulting double-layer stratification is stable to classical Rayleigh-Taylor or buoyancy-driven instabilities due to differential diffusion mechanisms, such as double-diffusion or double-layer-convection scenarios, and thus it is ideal to isolate the pure effect of cross-diffusion on the system stability. 

Budroni, M.A., Rossi, F. A novel mechanism for in situ nucleation of spirals controlled by the interplay between phase fronts and reaction diffusion waves in an oscillatory medium. J. Phys. Chem. C 119(17), 9411-9417 (2015) Carballido-Landeira, J., Trevelyan, P.M.J., Almarcha, C., De Wit, A. Mixed-mode instability of a miscible interface due to coupling between Rayleigh-Taylor and double-diffusive convective modes. Phys. Fluids 25(2), 024107 (2013)... 

In a simplified model, this representation reflects a bilinear autocatalytic reaction B + N -> 2B, and simply means that the bacteria needs nutrient (assume no shortage of nutrient) to double themselves (Muller and Saarloos, 2002). Any instability observed for k > 0 is due to the nonlinearity in the diffusion coefficient. With the relations above, the reaction-diffusion system becomes... 

Experimentally it has been shown that the threshold pressure at which combustion instability can be induced artificially in composite proplnts by pulsing is a function of the burning rate of the proplnt (in a motor size of 5-inch diameter and 40-inch length) (Ref 45). This relationship is shown in Figs 17 and 18 for both aluminized and non-aluminized composite proplnts. It was also found that potassium perchlorate, lithium perchlorate and AN proplnts were resistant to this induced instability. Since AP composites were the only proplnts, other than double-base, which were driven unstable, the rate controlling reactions and response function are those related to AP decompn and perhaps the diffusion flame between oxidizer and binder... 

ELECTROCHEMICAL INSTABILITY AT LIQUID/UQUID INTERFACES charge density in W. Similarly, for the diffuse part of the double layer in O,... 

For a given system, the quantities A and Zb are fixed, so that varying the electrolyte (in type and concentration) should produce instability at a particular value of Vk (Filers and Korff rule). To the extent that measures the potential characterizing the diffuse part of the electrical double layer, it is hardly surprising that it should provide a good description of the dispersion-coagulation process. 

In order to sustain the ON state by double injection or by tunneling it is necessary, as Lucas (1971) points out, that the carrier lifetime is longer than the transit time. Her model of switching is based on the idea that beyond a critical injection current both electron and hole traps are neutralized and as a consequence recombination is sharply decreased and the diffusion length becomes of the order of the film thickness. This sharply increases the bulk conductance and the sustaining field is again concentrated at the electrodes as in Figure 6.21(c). Lucas obtains for the critical current density at which the so-called recombination instability occurs... 

Budroni, M.A. Cross-diffusion-driven hydrodynamic instabilities in a double-layer system general classification and nonlinear simulations. Phys. Rev. E 92(6), 063007 (2015)... 

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