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SUMMARY:Physicochemical hydrodynamics of droplets in inkjet printing
DTSTART:20221013T101500
DTEND:20221013T111500
DTSTAMP:20260502T005714Z
UID:9082838817014cf82e0aabf5db2e9e0ea89338ee48fad0821785f76e
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Detlef Lohse\nAbstract :\nInkjet printing is the most wi
 despread technological application of microfluidics. It is characterized b
 y its high drop productivity\, small volumes and extreme reproducibility. 
 In this talk I will give a synopsis of the fluid dynamics of inkjet printi
 ng and discusses the main challenges for present and future research [1]. 
 These lie both on the printhead side – namely the detailed flow inside t
 he printhead\, entrained bubbles\, the meniscus dynamics\, wetting phenome
 na at the nozzle plate\, and jet formation – and on the receiving substr
 ate side – namely droplet impact\, merging\, wetting of the substrate\, 
 droplet evaporation\, and drying. In most cases the droplets are multicomp
 onent\, displaying rich physicochemical hydrodynamic phenomena [2]. The ch
 allenges on the printhead side and on the receiving substrate side are int
 erwoven\, as optimizing the process and the materials with respect to eith
 er the printhead side or the substrate side is not enough: As the same ink
  (or other jetted liquid) is used and as droplet frequency and size matter
  on both sides\, the process must be optimized as a whole. One example for
  conflicting requirements from the printhead side on the one hand and from
  the receiving substrate or more specifically the paper side on the other 
 hand is the volatility of the ink: At the nozzle\, it would be preferable 
 if the evaporation of ink were avoided to prevent nozzle clogging\, but on
  the paper side\, fast evaporation of ink is desirable to enable productiv
 e printing and to prevent paper deformation.\n\nEven such a seemingly simp
 le process as the evaporation of multicomponent droplets keeps surprising 
 us through its richness of phenomena. I will show and explain several of s
 uch phenomena\, namely evaporation-triggered segregation thanks to either 
 weak solutal Marangoni flow or thanks to gravitational effects. The domina
 nce of the latter implies that sessile droplets and pending droplets show 
 very different evaporation behavior\, even for Bond number << 1. I will al
 so explain the full phase diagram in the Marangoni number vs Rayleigh numb
 er phase space\, and show where Rayleigh convections rolls prevail\, where
  Marangoni convection rolls prevail\, and where they compete\, and why the
 se processes are very important in piezoacoustic inkjet printing. I will a
 lso extend these considerations to ternary and colloidal droplets and show
  and explain the new\, fascinating\, and often counter-intuitive phenomena
  which occur for these case of complex ink droplets.\n[1] Detlef Lohse\, A
 nnu. Rev. Fluid Mech. 54\, 349-382 (2022).\n[2] Detlef Lohse and Xuehua Zh
 ang\, Nature Rev. Phys. 2\, 426-443 (2020).\n\nSpeaker’s Bio\nDetlef Loh
 se studied physics at the Universities of Kiel & Bonn (Germany)\, and got 
 his PhD at Univ. of Marburg (1992). He then joined Univ. of Chicago as pos
 tdoc. After his habilitation (Marburg\, 1997)\, in 1998 he became Chair at
  Univ. of Twente in the Netherlands and built up the Physics of Fluids gro
 up. Since 2015 he is also Member of the Max Planck Society and of the Max-
 Planck Institute in Göttingen. Lohse's present research interests include
  turbulence and multiphase flow and micro- and nanofluidics (bubbles\, dro
 ps\, inkjet printing\, wetting). He does both fundamental and more applied
  science and combines experimental\, theoretical\, and numerical methods.\
 n\nLohse is Associate Editor of J. Fluid Mech. (among others journals) and
  serves as Chair of the Executive Board of the Division of Fluid Dynamics 
 of the American Physical Society and Member of the Executive Board of IUTA
 M. He is Member of the (American) National Academy of Engineering (2017)\,
  of the Dutch Academy of Sciences (KNAW\, 2005)\, the German Academy of Sc
 iences (Leopoldina\, 2002) and Fellow of APS (2002). He won various scient
 ific prizes\, among which the Spinoza Prize (NWO\, 2005)\, the Simon Stevi
 n Meester Prize (STW\, 2009)\, the Physica Prize of the Dutch Physics Soci
 ety (2011)\, the AkzoNobel Science Award (2012)\, two European Research Co
 uncil Advanced Grants (2010 & 2017)\, the George K. Batchelor Prize (IUTAM
 \, 2012)\, the APS Fluid Dynamics Prize (2017)\, the Balzan Prize (2018)\,
  and the Max Planck Medal (2019). In 2010\, he got knighted to become “R
 idder in de Orde van de Nederlandse Leeuw”.\n\n 
LOCATION:BM 5202 https://plan.epfl.ch/?room==BM%205202 https://epfl.zoom.u
 s/j/65951900855
STATUS:CONFIRMED
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