Gels near-critical fluids

Let us examine the critical dynamics near the bulk spinodal point in isotropic gels, where K + in = A(T — Ts) is very small, Ts being the so-called spinodal temperature [4,51,83-85]. Here, the linear theory indicates that the conventional diffusion constant D = (K + / )/ is proportional to T — Ts. Tanaka proposed that the density fluctuations should be collectively convected by the fluid velocity field as in near-critical binary mixtures and are governed by the renormalized diffusion constant (Kawasaki s formula) [84],... 

When choosing a mixer for gel preparation, the common approach is to test available mixers until one is found which adequately performs the tasks described previously. Although this is largely a hit-or-miss approach, it is apparently not too critical, and many suitable candidate fuel slurries have been prepared. Similar end products can be obtained with different mixing devices. At present non-Newtonian fluid mixing remains more of an art than a science, and the outlook is that it will remain as such in the near future. 

Here, the spatial derivatives on and p are taken with respect to the real position X. The first term in Eq. (3.13) is of the well-known form in the dynamical model of fluid binary mixtures near the critical point [34, 35]. This ought to be the case because our model reduces to that of fluids for v0 = 0. The last term in Eq. (3.13) is the elastic contribution, AT(jco) being a function of the original position jc0- If the gel is in mechanical equilibrium, we should require = 0 within the gel. 

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