Molecular diffusion, effect

At high Reynolds numbers where molecular diffusion effects are negligible, experimental evidence confirms the general validity of equation 12.7.5. Figure 12.15 indicates how the Peclet number for radial mixing varies with the fluid Reynolds number. Above a Reynolds number of 40, the radial Peclet number is approximately 10. 

Bilger, R. W. and R. W. Dibble (1982). Differential molecular diffusion effects in turbulent mixing. Combustion Science and Technology 28, 161-169. 

Providing the echo interval in WATERGATE is kept short to minimize /-modulation, T2 relaxation and molecular diffusion effects (i.e. note the similarity with the Hahn spin-echo-based PGSE sequence in Fig. 9B), the desired resonances are retained in the spectrum with near-full intensity while the water peak should be suppressed by a factor of at least 1(1. Scalar coupling evolution can be refocused if the ir pulse in the WATERGATE sequence excites only some of the solute resonances but not the scalar coupled partners (for example amide resonances). ... 

Sorbie, K.S., and P.J. Clifford. 1991. The inclusion of molecular diffusion effects in the network modelling of hydrodynamic dispersion in porous media. Chem. Eng. Sci. 46 2525-2542. 

At high Reynolds numbers where molecular diffusion effects are negligible, experimental evidence confirms the... 

It requires a finite time for the effects of k to be appreciable so that the moment Eqs. (25.18) to (25.22) provide a small-time approximation, in the case of a cloud (or near-source in the case of a steady release), to the true k 0 result. The time period required for molecular diffusive effects to reduce concentration is generally large with respect to the time periods over which large-scale turbulent convective motions provide significant displacements of contaminant fluid. Thus, many qualitative features of the moment Eqs. (25.18) to (25.22) are observed in experimental flows. 

It was also reported that the polarity of the oily phase enhances the molecular diffusion effect. Thus, the addition of a nonpolar ingredient, such as alcanes, fatty alcohols, and fatty amides to polar oily droplets can improve the stability when the droplet size is small. 

---