Random walk in an eddy and tube formation from fine particles

Tubular shape formation of an ensemble of ultrafine particles, captured by microscopic eddies in a fluid or gaseous medium, is investigated. In the ci rculation flow of the eddy, the small particles are driven by the determini stic hydrodynamical forces and the random forces of Brownian motion. The co nditions for dynamically/statistically stable tube formation and the result ing tube parameters are obtained by analytic calculations and computer simu lations, respectively. The model yields striking similarities to the charac teristics of nanotube formation observed in turbulent media such as the car bon arc, and throws some light on tubular formation observed in fluid media . (C) 2001 American Institute of Physics.