New criteria for filament breakup in droplet-on-demand inkjet printing using volume of fluid (VOF) method

• Published in: The Korean journal of chemical engineering Vol. 33; no. 3; pp. 775 - 781
• Main Authors: Poozesh, Sadegh, Akafuah, Nelson, Saito, Kozo
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2016; 한국화학공학회
• Subjects: Biotechnology; Catalysis; Chemistry; Chemistry and Materials Science; Industrial Chemistry/Chemical Engineering; Materials Science; Transport Phenomena; 화학공학; Volume of Fluid (VOF); Droplet on Demand; Scale Modelling; Filament Breakup; Inkjet Printing
• ISSN: 0256-1115; 1975-7220
• DOI: 10.1007/s11814-015-0197-5

A volume of fluid (VOF) numerical study is presented in which new pi number-based criteria are discussed that identify and separate three different regimes for a droplet-on-demand (DOD) print-head system. A trailing filament coalesces into the main droplet while the filament breaks into one or multiple satellite droplet(s). The numerical simulation results are compared with published large-scale experimental results that used a 2 mm diameter inkjet nozzle head, roughly 50 times larger than the actual diameter of inkjet outlets. Liquid filament break-up behavior is predicted using a combination of two pi-numbers, including either Weber (We)-Ohnesorge (Oh) number couplets or Reynolds (Re)-Weber (We) number couplets that are dependent only on the ejected liquid properties and the velocity waveform at the print-head inlet. These new criteria have merit over the currently existing ones that require accurate measurements of actual droplets to determine filament physical features like length and diameter [1].