Phase behavior of binary fluid mixtures confined in a model aerogel

It is found experimentally that the coexistence region of a vapor-liquid sy stem or a binary mixture is substantially narrowed when the fluid is confin ed in an aerogel with a high degree of porosity (e.g., of the order of 95 t o 99%). A Hamiltonian model for this system has recently been introduced [1 ]. We have performed Monte-Carlo simulations for this model to obtain the p hase diagram for the model. We use a periodic fractal structure constructed by diffusion-limited cluster-cluster aggregation (DLCA) method to simulate a realistic gel environment. The phase diagram obtained is qualitatively s imilar to that observed experimentally. We also have observed some metastab le branches in the phase diagram which have not been seen in experiments ye t. These branches, however, might be important in the context of recent the oretical predictions and other simulations.