Published in Physics World, 22 Feb 2012
A filament of liquid squirted from a nozzle will sometimes contract into a single drop and other times break up into many segments. Now, researchers in the UK have mapped the parameters that will lead a filament to break up, and they believe that this knowledge could help in the design of inkjet printers.
Inkjet printing requires single drops of ink to be deposited on paper, and for this reason engineers are keen to avoid conditions that would encourage ink filaments squirted from an inkjet nozzle to break up. Theory shows that there are several crucial parameters: the liquid’s density, viscosity and surface tension – all three of which can be grouped into a single “Ohnesorge number”. The other is the aspect ratio, which describes the filaments’ length in relation to diameter. In general, longer filaments with a high aspect ratio, and filaments with a small Ohnesorge number, are likely to break up. […]
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