Controlling drop impact by additives

Condensed Matter lunchtime seminar

Controlling drop impact by additives

  • Event time: 1:00pm
  • Event date: 20th March 2006
  • Speaker: Volfango Bertola (School of Engineering)
  • Location: Room 6206,

Event details

Whether painting, printing, cooling or simply cleaning surfaces, spraying a fluid onto them is an event we encounter daily. However, in many cases the processes involved are very complex and a multitude of different factors need to be considered. According to the fluid properties, the impact velocity, and the surface roughness, drops may either stick to the wall, or hit the wall and bounce off, or break-down upon impact into smaller droplets; on the other hand, the size and size distribution of drops in sprays is often determined by design or environmental constraints.

Recent advances in our understanding of 'complex fluids' have led to the development of chemical additives that greatly improve spray applications. In this seminar the effects of additives on drop impact phenomena are reviewed, with special attention to the effects of flexible polymer additives. The results can be interpreted in terms of a coil-stretch transition of polymer molecules driven by the hydrodynamic action of the surrounding fluid: at rest, polymer molecules are coiled in a minimum energy conformation, whereas if the hydrodynamic forces are sufficiently large they unfold, opposing an increasing resistance to deformation as they are stretched.

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

Find out more about Condensed Matter lunchtime seminars.