Numerical Simulation of Digital Microfluidics Based on Electro-Dynamic Model

2012 ◽  
Vol 2 (3) ◽  
pp. 14-23
Author(s):  
Liguo Chen ◽  
Mingxiang Ling ◽  
Deli Liu
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Contact Line ◽  
Contact Area ◽  
Digital Microfluidics ◽  
Phase Contact ◽  
Electrowetting On Dielectric ◽  
Three Phase ◽  
Internal Mechanism ◽  
Contact Domain

Aiming at the doubt and divarication about the internal mechanism of electrowetting on dielectric (EWOD) in digital microfluidics, the authors attempted to explain the internal mechanism of EWOD through electro-dynamic-based numerical simulation model. First, the boundary conditions for the governing equation were found. Then the influence of mesh number on simulation results was analyzed and feasibility of the simulation model was verified by comparing numerical results with theoretical ratiocination. Finally, they compared the electro-dynamic actuation force acting on the surface of droplet on three digital microfluidic structures, which have the same three-phase contact line but different area of contact domain. Analytical results showed that electro-dynamic force generated solely by the accumulation of induced charges in contact domain was three times larger than that generated by three-phase contact line. Induced charges accumulated on both three-phase contact line and contact area of droplet gave the contribution to EWOD, but contact area played a major role in the change of contact angle of droplet.

Direct Numerical Simulation of the Microscale Fluid Flow and Heat Transfer in the Three-Phase Contact Line Region During Evaporation

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Stefan Batzdorf ◽  
Tatiana Gambaryan-Roisman ◽  
Peter Stephan
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Contact Line ◽  
Thin Liquid Film ◽  
Contact Angles ◽  
Length Scale ◽  
Phase Contact ◽  
Flow And Heat Transfer ◽  
Three Phase

The heat and mass transfer close to the apparent three-phase contact line is of tremendous importance in many evaporation processes. Despite the extremely small dimensions of this region referred to as the microregion compared to the macroscopic length scale of a boiling process, a considerable fraction of heat can be transferred in this region. Due to its small characteristic length scale, physical phenomena are relevant in the microregion, which are completely negligible on the macroscopic scale, including the action of adhesion forces and the interfacial heat resistance. In the past, models have been developed taking these effects into account. However, so far these models are based on the assumption of one-dimensional (1D) heat conduction, and the flow within the thin liquid film forming the microregion near the apparent three-phase contact line is modeled utilizing the lubrication approximation. Hence, the application of existing models is restricted to small apparent contact angles. Moreover, the effects of surface structures or roughness are not included in these lubrication models. To overcome these limitations, a direct numerical simulation (DNS) of the liquid flow and heat transfer within the microregion is presented in this paper. The DNS is employed for validation of the existing lubrication model and for investigation of the influence of surface nanostructures on the apparent contact angle and in particular on the heat transfer within the microregion.

On the interpretation of contact angle for geomaterial wettability: Contact area versus three-phase contact line

2020 ◽  
Vol 195 ◽  
pp. 107579 ◽  
Author(s):  
Emad Sadeghinezhad ◽  
Mohammed Abdul Qadeer Siddiqui ◽  
Hamid Roshan ◽  
Klaus Regenauer-Lieb
Keyword(s):  
Contact Angle ◽  
Contact Line ◽  
Contact Area ◽  
Phase Contact ◽  
Three Phase

Test of the stability of a three-phase contact line with negative line tension

1999 ◽  
Vol 96 (9) ◽  
pp. 1335-1339 ◽  
Author(s):  
ALAN E. VAN GIESSEN, DIRK JAN BUKMAN, B.
Keyword(s):  
Contact Line ◽  
Line Tension ◽  
Phase Contact ◽  
Three Phase ◽  
The Stability

Faster Nucleation of Ice and Carbon Dioxide Hydrates at the Three-Phase Contact Line

2021 ◽  
Author(s):  
Aritra Kar ◽  
Awan Bhati ◽  
Palash V. Acharya ◽  
Ashish Mhadeshwar ◽  
Roger Bonnecaze ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Contact Line ◽  
Phase Contact ◽  
Three Phase

Effect of Charge Distribution at the Three Phase Contact Line for an Electrolyte Drop

2013 ◽  
Author(s):  
Dibyo Sarkar ◽  
Siddhartha Das ◽  
Sushanta K. Mitra
Keyword(s):  
Velocity Field ◽  
Electrolyte Solution ◽  
Contact Line ◽  
Electric Double Layer ◽  
Charged Surface ◽  
Electrokinetic Transport ◽  
Phase Contact ◽  
Advective Flux ◽  
Three Phase ◽  
First Time

In this paper, we obtain the velocity field in a wedge in a Three Phase Contact Line (TPCL) in an electrolyte drop which is evaporating on a charged solid. Combination of an electrolyte solution and the charged surface leads to the formation of an Electric Double Layer (EDL), which in presence of the evaporation-triggered pressure-driven transport, leads to the generation of a streaming current that causes an electrokinetic transport. Hence, we analyze for the first time an electrokinetic transport in a charged wedge in presence of an evaporation-induced advective flux. Our results exhibit flow patterns that are distinctly different as compared to that of the case where there is no such electrokinetic transport and the problem is merely that of evaporation in a wedge.

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