Travelling isothermal waves

TRAVELLING ISOTHERMAL WAVES MAINTAINED BY CUBIC AUTOCATALYSIS ONEDIMENSIONAL CASE... 

This chapter deals principally with travelling wavefronts of chemical reactions of uniform speed and constant concentration profile but also considers pulses and periodic wave trains. Isothermal cubic autocatalysis offers deep insights into the phenomenon as a whole. After careful study the reader should be able to ... 

The next important step in the study of the regularities of the autowave modes of cryochemical conversion was to perform a series of experiments with thin-film samples of reactants. The changeover to such objects, characterized by the most intense heat absorption, allowed the realization of quasi-isothermal conditions of the process development and thus favored the manifestation of the abovementioned isothermal mechanism of wave excitation, which involves autodispersing the sample layer by layer due to the density difference between the initial and final reaction products. The new conditions not only not suppressed the phenomenon, but made it possible to reveal some details of the traveling-wave-front structure, which will be discussed here and also in Section X. 

An accurate study of the temperature profile structure in film and capillary samples involves considerable technical difficulties, which accounts for the lack of direct information on the role of the isothermal and nonisothermal mechanisms in the systems considered. However, some features of the structure are evident from the cinegram of Fig. 9. It shows that the wave front traveling in a capillary is noticeably ahead of the zone of intense reaction-heat release, marked by violent boiling of liquid helium in the cryostat. This observation allows the conclusion that here the fore part of the wave front is located in the not yet heated portion of the sample that is, small degrees of... 

The above referenced experiments (adiabatic) occur in flow geometries much more complicated than the simple (isothermal) planar Riemann (shock structure) problems discussed above. Furthermore, the interesting results on shock splitting given in [27], [41-44] all involved piston and not Riemann initial value problems. Hence a direct comparison with the local shock structure theory given here may be difficult. Nonetheless for completeness we record some obvious consistencies and discrepancies between the experimental results and traveling wave theory. 

With respect to the fact that traveling wave theory given above was isothermal while the experiments axe not we recall that the papers [40], [21] show that the same qualita-... 

The wavefront "sees" only a uniformly pretreated and isothermal catalyst independent of a temperature change if the front has passed, since the thermal wave travels much slower than the... 

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