Predicting the onset of hydrate nucleation in oil pipelines is one of the most challenging aspects in the flow assurance modelling work being performed at the Center for Hydrate Research. Nucleation is initiated by a random fluctuation which is able to overcome the energy barrier for the phase transition, once such a fluctuation occurs, further growth is energetically favourable. Historically t...

We study the conditions under which and how an imposed cluster of fixed colloidal particles at prescribed positions triggers crystal nucleation from a metastable colloidal fluid. Dynamical density functional theory of freezing and Brownian dynamics simulations are applied to a two-dimensional colloidal system with dipolar interactions. The externally imposed nucleation clusters involve colloida...

We consider the effect of molecular anisotropy and dipole moment on the rate of homogeneous and heterogeneous nucleation of molecular and dipolar fluids. Density functional theory is applied to an interaction site model of molecules composed of two tangent or fused hard spheres interacting through Lennard-Jones and coulombic potentials. Interfacial properties are conditioned by entropy vs energ...

Magnetic relaxation measurements were carried out by magneto-optical Kerr effect on exchange biased (Pt/Co)5/Pt/FeMn multilayers with perpendicular anisotropy. In these films the coercivity and the exchange bias field vary with Pt spacer thickness, and have a maximum for 0.2 nm. Hysteresis loops do not reveal important differences between the reversal for ascending and descending fields. Relaxa...

The nucleation and growth of Co clusters on vacuum-annealed (reduced) and oxidized TiO2(110) have been studied by scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and density function theory (DFT) calculations. On vacuum-annealed TiO2(110), the Co clusters grow as three-dimensional islands at coverages between 0.02 and 0.25 ML, but the cluster heights range from ∼3 t...

R. J. Benjamin A. R. Balakrishnan Department of Chemical Engineering, Indian Institute of Technology Madras, Madras 600 036, India • An experimental investigation on the nucleation density during nucleate pool boiling of saturated pure liquids at low to moderate heat fluxes is described. The surface-liquid interaction during the boiling phenomena and its effect on the nucleation site density an...

The Van der Waals-Cahn-Hilliard gradient theory (GT) is applied to determine the structure and the work of formation of clusters in supersaturated n-nonane vapor. The results are analyzed as functions of the difference of pressures of the liquid phase and vapor phase in chemical equilibrium, which is a measure for the supersaturation. The surface tension as a function of pressure difference sho...

A theoretical description of heterogeneous nucleation kinetics is presented. This description takes into account the perturbation of the vapor phase initiated by the growing droplets. The form of the density profile around the growing droplet is analyzed and some special approximations are given. Then the process of nucleation in the whole system is described. As a result all the main character...

– Fully deterministic calculations of the dynamics of island nucleation and growth during thin-film deposition are presented, using a capture zone model that transcends the classical mean-field approximation. Nucleation rates for various critical island sizes i = 0, 1, 2 are accurately calculated from the time-dependent monomer density within the capture zones. The deterministic evolution of th...

We present a Ginzburg-Landau theory of ion-induced nucleation in a gas phase of polar one-component fluids, where a liquid droplet grows with an ion at its center. By calculating the density profile around an ion, we show that the solvation free energy is larger in gas than in liquid at the same temperature on the coexistence curve. This difference much reduces the nucleation barrier in a metas...