title: Influence of film dimensions on film droplet formation.
abstract: BACKGROUND
  Aerosol particles may be generated from rupturing liquid films through a droplet formation mechanism. The present work was undertaken with the aim to throw some light on the influence of film dimensions on droplet formation with possible consequences for exhaled breath aerosol formation.
  
  
  METHODS
  The film droplet formation process was mimicked by using a purpose-built device, where fluid films were spanned across holes of known diameters. As the films burst, droplets were formed and the number and size distributions of the resulting droplets were determined.
  
  
  RESULTS
  No general relation could be found between hole diameter and the number of droplets generated per unit surface area of fluid film. Averaged over all film sizes, a higher surface tension yielded higher concentrations of droplets. Surface tension did not influence the resulting droplet diameter, but it was found that smaller films generated smaller droplets.
  
  
  CONCLUSIONS
  This study shows that small fluid films generate droplets as efficiently as large films, and that droplets may well be generated from films with diameters below 1 mm. This has implications for the formation of film droplets from reopening of closed airways because human terminal bronchioles are of similar dimensions. Thus, the results provide support for the earlier proposed mechanism where reopening of closed airways is one origin of exhaled particles.
authors.affiliation: Environmental Inorganic Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden. heleneh@chalmers.se
authors.forename: Helene
authors.initials: H
authors.lastname: Holmgren
authors.forename: Evert
authors.initials: E
authors.lastname: Ljungström
mesh_terms: D000336:Aerosols; D006801:Humans; D010316:Particle Size; D013500:Surface Tension
chemical_list: D000336:Aerosols