Michael Moseler and Uzi Landman
August 18, 2000 issue of Science
Embargoed for Release August 17, 2 p.m. U.S. Eastern Time
Copyright: Science
Copyright: Science
(B) Evolution of the propane nanojet along the direction of propagation at selected times after exit from the nozzle. Formation of fast moving droplets and molecular clusters is observed at the initial (transient) state, achieving steady-state flow conditions. Molecular evaporation and formation of necking instabilities are observed, leading to breakup events and formation of drops. At pinch-off, the droplets are of elongated ellipsoidal shape and they round-up shortly after.
In the inset, the time evolution of the intact length of the jet is shown. Each saw-tooth discontinuity corresponds to a pinch off of a drop.
(A-C) Selected atomistic configurations obtained via molecular dynamics simulations with a wetting 6 nm diamater nozzle, illustrating various breakup scenarios. In each frame, two consecutive times are shown. The most frequently observed breakup process, exhibiting close to pinch-off formation of an axis-symmetric double-cone shape of the neck, is displayed in (B).
Also shown is (A) occasional formation of a non-axisymmetric neck-configuration or (C) generation of a somewhat elongated neck resulting in split-off of a small cluster. (D) Results pertaining to breakup events of the propane jet for the above non-wetting nozzle obtained via an atomistic molecular dynamics simulation (top); a simulation using the deterministic lubrication equations LE; a simulation of the stochastic LE, SLE. Note the double-cone neck shapes exhibited in the MD and SLE simulation, on contrast to the long thread obtained with the LE. (E) shows the time evolution of the intact jet length L (upper curve) and for the minimal jet radius (bottom curve).
