Particle dynamics in stream channels from molecular dynamics

Hydrodynamics is an important scientific field for investigating and characterizing fluids. This work presents a novel method for studying fluids at the atomic level using molecular dynamics. The fluids flow in closed channels and under conditions of pressure and temperature. The method has the advantage of avoiding the difficulties traditionally encountered in formulating and solving the Navier-Stokes equations in combination with periodic boundary conditions. In this work, the stream channels are simulated with confining potentials, making the method efficient, general, and flexible enough to represent different channel topologies. It is illustrated with the simulation of water molecules flowing inside an elongated toroidal pipeline, with many small gold clusters suspended in the fluid. The clusters coalesce and form aggregates with average sizes that depend on the water velocity. The results suggest a new experimental approach for the formation of large clusters from small ones by tuning the flux rate in the laboratory experiments. The method is the first of its kind and opens new horizons for studying hydrodynamic processes at the atomic level employing first-principles theory.