scholarly journals A Dynamical Model of Drop Spreading in Electrohydrodynamic Jet Printing

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Christopher P. Pannier ◽  
Mamadou Diagne ◽  
Isaac A. Spiegel ◽  
David J. Hoelzle ◽  
Kira Barton
Keyword(s):  
Contact Angle ◽  
Additive Manufacturing ◽  
Optical Sensors ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Initial Contact ◽  
Drop Volume ◽  
Spherical Cap ◽  
Jet Printing ◽  
Base Radius

Electrohydrodynamic jet (e-jet) printing is a microscale additive manufacturing technique used to print microscale constructs, including next-generation biological and optical sensors. Despite the many advantages to e-jet over competing microscale additive manufacturing techniques, there do not exist validated models of build material drop formation in e-jet, relegating process design and control to be heuristic and ad hoc. This work provides a model to map deposited drop volume to final spread topography and validates this model over the drop volume range of 0.68–13.4 pL. The model couples a spherical cap volume conservation law to a molecular kinetic relationship for contact line velocity and assumes an initial contact angle of 180 deg to predict the drop shape dynamics of dynamic contact angle and dynamic base radius. For validation, the spreading of e-jet-printed drops of a viscous adhesive is captured by high-speed microscopy. Our model is validated to have a relative error less than 3% in dynamic contact angle and 1% in dynamic base radius.

scholarly journals Fabrication of micro-structured surfaces by additive manufacturing, with simulation of dynamic contact angle

2019 ◽  
Vol 176 ◽  
pp. 107839 ◽  
Author(s):  
Ali Davoudinejad ◽  
Yukui Cai ◽  
David Bue Pedersen ◽  
Xichun Luo ◽  
Guido Tosello
Keyword(s):  
Contact Angle ◽  
Additive Manufacturing ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Structured Surfaces

scholarly journals Not spreading in reverse: The dewetting of a liquid film into a single drop

2016 ◽  
Vol 2 (9) ◽  
pp. e1600183 ◽  
Author(s):  
Andrew M. J. Edwards ◽  
Rodrigo Ledesma-Aguilar ◽  
Michael I. Newton ◽  
Carl V. Brown ◽  
Glen McHale
Keyword(s):  
Contact Angle ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Equilibrium Contact Angle ◽  
Droplet Spreading ◽  
Spherical Cap ◽  
Liquid Marbles ◽  
Exponential Relaxation ◽  
Wetting Process ◽  
Fluid Manipulation

Wetting and dewetting are both fundamental modes of motion of liquids on solid surfaces. They are critically important for processes in biology, chemistry, and engineering, such as drying, coating, and lubrication. However, recent progress in wetting, which has led to new fields such as superhydrophobicity and liquid marbles, has not been matched by dewetting. A significant problem has been the inability to study the model system of a uniform film dewetting from a nonwetting surface to a single macroscopic droplet—a barrier that does not exist for the reverse wetting process of a droplet spreading into a film. We report the dewetting of a dielectrophoresis-induced film into a single equilibrium droplet. The emergent picture of the full dewetting dynamics is of an initial regime, where a liquid rim recedes at constant speed and constant dynamic contact angle, followed by a relatively short exponential relaxation of a spherical cap shape. This sharply contrasts with the reverse wetting process, where a spreading droplet follows a smooth sequence of spherical cap shapes. Complementary numerical simulations and a hydrodynamic model reveal a local dewetting mechanism driven by the equilibrium contact angle, where contact line slip dominates the dewetting dynamics. Our conclusions can be used to understand a wide variety of processes involving liquid dewetting, such as drop rebound, condensation, and evaporation. In overcoming the barrier to studying single film-to-droplet dewetting, our results provide new approaches to fluid manipulation and uses of dewetting, such as inducing films of prescribed initial shapes and slip-controlled liquid retraction.

Investigation of behavior of the dynamic contact angle in a problem of convective flows

2017 ◽  
Vol 5 (4) ◽  
pp. 27-42
Author(s):  
O.N Goncharova ◽  
◽  
I.V. Marchuk ◽  
A.V. Zakurdaeva ◽  
◽  
...  
Keyword(s):  
Contact Angle ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Convective Flows

Effect on Sedimentation Characteristics of Bentonite Suspension at Different Conditions

2013 ◽  
Vol 333-335 ◽  
pp. 2004-2009
Author(s):  
Lin Ling Jiang ◽  
Wei Mo ◽  
Xiao Jing Yang ◽  
Tian Li Xue ◽  
Shao Jian Ma
Keyword(s):  
Contact Angle ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Sodium Pyrophosphate ◽  
Sedimentation Rates ◽  
Sedimentation Analysis ◽  
Ph Values ◽  
Bentonite Suspension ◽  
Sedimentation Time ◽  
Sedimentation Processes

To better understand the sedimentation processes of bentonite, the sedimentation characteristic of bentonite suspension was studied by using the sedimentation analysis module of Dynamic Contact Angle Meter and Tensiometer. The results indicated that sedimentation characteristics of bentonite suspension were affected by the concentration and pH values of the suspension together with the dosage of dispersants. The natural sedimentation rates of bentonite suspension declined firstly with prolonging the sedimentation time and soon stabilized after about 50s. The sedimentation weight of particles hardly changed when the concentration ranged from 0.5% to 5.0%, while it increased significantly when ranged from 5.0% to 10.0%. The sedimentation weight and rate were relatively bigger at 4.4, 11.8 than that of 6.0, 7.9, and the maximum values appeared at pH11.8. Adding sodium pyrophosphate could improve the dispersibility of bentonite suspension.

Surface dynamics for poly(vinyl alkylate)s via dynamic contact angle and adhesion tension relaxation

Polymer ◽  
1996 ◽  
Vol 37 (16) ◽  
pp. 3659-3664 ◽  
Author(s):  
T. Kasemura ◽  
S. Takahashi ◽  
N. Nakane ◽  
T. Maegawa
Keyword(s):  
Contact Angle ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
Surface Dynamics
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