MODELING GROWTH PATTERN FORMATION IN A VERTICALLY ORIENTED THIN-LAYER CELL ELECTRODEPOSITION

E. MOCSKOS, G. GONZÁLEZ, G. MARSHALL, S. DENGRA,F. V. MOLINA

Buenos Aires, Argentina

Congreso; MECOM2005 Congreso Argentino de Mecánica Computacional; 2005

ASOCIACIÓN ARGENTINA DE MECANICA COMPUTACIONAL

Electrodeposition in a thin cell (ECD) in a vertical position, with the cathode above the anode, yields a growth pattern formation whose signature is a dense branched morphology. However, detailed analysis of front evolution reveals a complex competition between neighboring  branches leading to a locally fluctuating growth. Here we study the nature of this quasi equilibrium growth through a new macroscopic model and its numerical simulation. The model, based on first principles, uses the Nernst-Planck equations for ion transport, the Poisson equation for the electrostatic potential, the Navier-Stokes equations for the fluid flow and a new growth model, based on a Dielectrical Aggregation Model (DBM), for deposit growth. Numerical simulations in realistic 3D cells using serial and parallel computing are presented; in the latter use is made of domain decomposition techniques with a strongly implicit iterative method implemented in a Beowulf cluster under MPI and Linux. This allows the utilization of very fine grids with a more realistic physical parameterization and results in a robust scalable algorithm attaining almost linear speedup. Theory and simulations predict the detachment of the leading branch from its neighbors, an enlargement of its tip in the form of a mushroom, and a deceleration of its front speed until the lagging branches catch with the leader, in qualitative agreement with experimental observations.