Critical length scale, definition

Thus, the available data related to transition in circular micro-tubes testify to the fact that the critical Reynolds number, which corresponds to the onset of such transition, is about 2,000. The evaluation of critical Reynolds number in irregular micro-channels will entail great difficulty since this problem contains a number of characteristic length scales. This fact leads to some vagueness in definition of critical Reynolds number that is not a single criterion, which determines flow characteristics. [Pg.123]

According to this definition dilute solutions of long macromolecules are critical. The role of the correlation length is played by the radius of gyration Rg rsj Nu — oo N — oo, and by virtue of the chain structure a polymer coil shows density fluctuations on all scales r < Rg. Indeed, a blob of size r is just a correlated fluctuation of the density. [Pg.168]

Since in Fig. 19 critical temperatures have been estimated by a rough extrapolation only, this study [39] could not make too definitive statements about the shift of the critical temperature due to confinement. A more extensive study has been possible for the bond fluctuation model [55], extracting both critical temperatures and the coexistence curves by use of the finite size scaling technique [236-239,280]. Figs.21, 22 present the results for chain length N=32. While mean field theory Eqs. (36) and (37) in Sect. 2.1 has predicted a crossover from... [Pg.54]

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