Summary of the IMA "Hot Topics" Workshop on Analysis and Modeling of Industrial Jetting Processes

Michael Brenner
Department of Mathematics
Massachusetts Institute of Technology
brenner@math.mit.edu

The meeting was a success beyond my expectation. Not only were the large majority of the talks of extremely high quality, but they complemented themselves very well, and in ways we did not anticipate when putting the program together. As an example, at least four speakers dealt with the phenomenon of a spherical drop of fluid splashing on a solid surface: David Wallace from MicroFab, our first speaker, described how the details of this question are crucial for depositing solder drops onto Flip-Chip semiconductor devices; Our third speaker, Ely Sachs from MIT, showed another beautiful example of this in the context of his three dimensional printing processes: drops depositing on a powder layer create craters, which limits the precision of their engineering. Then we had two, more scientific speakers, who touched on this subject: D. Poulikas from ETH showed his numerical simulations which clearly established the phenomenon as due to capillary waves. And then David Quere, from College de France, showed his beautiful experiments of drops bouncing on hydrophobic surfaces, which exposed the various regimes of bouncing drops. One of David's drops lifted off the solid surface in a shape close to a "baseball bat", which then oscillated through a complex series of shapes. Rather remarkably, another of our speakers, Osman Basaran from Purdue, had just presented a numerical simulation of fluid started in a baseball bat shape, and found a sequence of shapes which were very similar to those of Quere. Basaran's "baseball bat shapes" was motivated by a different experiment, the breaking of a pendant drop near a nozzle, a problem discussed in detail by some of the other speakers.

This is just an example of the types of interactions that occurred at the meeting. In a wide range of technologies, the same issues kept coming up again and again, even though the background and motivation of the speakers was very different. The combination of mathematics, engineering and technology at the same meeting allowed everyone to leave with a different perspective on the problems they have been thinking about previously.

"Hot Topics" Workshops

2000-2001 Program: Mathematics in Multimedia