arXiv subjects
Publications and source records attributed to Prabhat K. Jaiswal.
We study the early-stage kinetics of thermodynamically unstable systems with quenched disorder. We show analytically that the growth of initial fluctuations is amplified by the presence of disorder. This is confirmed by numerical simulations of morphological phase separation (MPS) in thin liquid films and spinodal decomposition (SD) in binary mixtures. We also discuss the experimental implications of our results.
We use molecular dynamics (MD) to study the kinetics of surface enrichment (SE) in a stable homogeneous mixture (AB), placed in contact with a surface which preferentially attracts A. The SE profiles show a characteristic double-exponential behavior with two length scales: ξ_-, which rapidly saturates to its equilibrium value, and ξ_+, which diverges as a power-law with time (ξ_+ \sim t^θ). We find that hydrodynamic effects result in a crossover of the growth exponent from θ\simeq 0.5 to θ\simeq 1.0. There is also a corresponding crossover in the growth dynamics of the SE-layer thickness.
We study spinodal phase separation in unstable thin liquid films on chemically disordered substrates via simulations of the thin-film equation. The disorder is characterized by immobile patches of varying size and Hamaker constant. The effect of disorder is pronounced in the early stages (amplification of fluctuations), remains during the intermediate stages and vanishes in the late stages (domain growth). These findings are in contrast to the well-known effects of quenched disorder in usual phase-separation processes, viz., the early stages remain undisturbed and domain growth is slowed down in the asymptotic regime. We also address the inverse problem of estimating disorder by thin-film experiments.
We study universality in the kinetics of spinodal phase separation in unstable thin liquid films, via simulations of the thin film equation. It is shown that in addition to morphology and free energy,the number density of local maxima in the film profile can also be used to identify the early, intermediate and late stages of spinodal phase separation. A universal curve between the number density of local maxima and rescaled time describes the kinetics of early stage in d = 2, 3. The Lifshitz-Slyozov exponent of -1/3 describes the kinetics of the late stage in d = 2 even in the absence of coexisting equilibrium phases.