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Molecular Dynamics Studies on Dynamic Wetting, Droplet Rapid Contact Line Advancement and Nanosuspension Drop Self-Pinning Phenomenon.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Molecular Dynamics Studies on Dynamic Wetting, Droplet Rapid Contact Line Advancement and Nanosuspension Drop Self-Pinning Phenomenon./
Author:	Shi, Baiou.
Description:	1 online resource (159 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 78-10(E), Section: B.
Contained By:	Dissertation Abstracts International78-10B(E).
Subject:	Mechanical engineering. -
Online resource:	click for full text (PQDT)
ISBN:	9781369846751

Molecular Dynamics Studies on Dynamic Wetting, Droplet Rapid Contact Line Advancement and Nanosuspension Drop Self-Pinning Phenomenon.
Shi, Baiou.

Molecular Dynamics Studies on Dynamic Wetting, Droplet Rapid Contact Line Advancement and Nanosuspension Drop Self-Pinning Phenomenon. - 1 online resource (159 pages)

Source: Dissertation Abstracts International, Volume: 78-10(E), Section: B.

Thesis (Ph.D.)

Includes bibliographical references

Droplet wetting and spreading across a solid substrate is a fascinating fluid mechanics phenomenon. Recently, the behavior of nano-fluids, or fluid suspensions containing nanoparticles, has garnered tremendous attention for applications in advanced manufacturing. Despite previous contributions, much remains to be understood about the wetting and spreading of nano-suspension drops especially on the fundamental mechanisms involved in the spreading process. However, due to the rapid contact line advancement and nano-scale droplet size, both experiments and continuum scale simulations could not provide ways to resolve the problem. Here, we use the fundamental time and length scale classical molecular dynamics to reveal the atomistic scale details about interfacial thermodynamics and associated forces during droplet wetting and spreading, i.e. to explore the related thermo-physical phenomena associated with capillary flow.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9781369846751Subjects--Topical Terms:

557493
Mechanical engineering.
Index Terms--Genre/Form:

554714
Electronic books.

Molecular Dynamics Studies on Dynamic Wetting, Droplet Rapid Contact Line Advancement and Nanosuspension Drop Self-Pinning Phenomenon.
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100 1 $a Shi, Baiou. $3 1178951
245 1 0 $a Molecular Dynamics Studies on Dynamic Wetting, Droplet Rapid Contact Line Advancement and Nanosuspension Drop Self-Pinning Phenomenon.
264 0 $c 2017
300 $a 1 online resource (159 pages)
336 $a text $b txt $2 rdacontent
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338 $a online resource $b cr $2 rdacarrier
500 $a Source: Dissertation Abstracts International, Volume: 78-10(E), Section: B.
500 $a Adviser: Edmund B. Webb.
502 $a Thesis (Ph.D.) $c Lehigh University $d 2017.
504 $a Includes bibliographical references
520 $a Droplet wetting and spreading across a solid substrate is a fascinating fluid mechanics phenomenon. Recently, the behavior of nano-fluids, or fluid suspensions containing nanoparticles, has garnered tremendous attention for applications in advanced manufacturing. Despite previous contributions, much remains to be understood about the wetting and spreading of nano-suspension drops especially on the fundamental mechanisms involved in the spreading process. However, due to the rapid contact line advancement and nano-scale droplet size, both experiments and continuum scale simulations could not provide ways to resolve the problem. Here, we use the fundamental time and length scale classical molecular dynamics to reveal the atomistic scale details about interfacial thermodynamics and associated forces during droplet wetting and spreading, i.e. to explore the related thermo-physical phenomena associated with capillary flow.
520 $a The first interest in my dissertation is to study the mechanisms of rapid contact line advance during the early stage of droplet spreading, i.e. the inertial regime spreading. Inertial regime spreading occurs at the earliest moment immediately following contact between a droplet and solid surface. It is at this point when a drop is most out of equilibrium and therefore experiences the highest capillary forces. For low viscosity liquids with high wettability, high contact line velocities are observed during this stage. Meanwhile, much remains unknown about mechanisms governing such rapid capillary flow during this stage; additionally, because the very leading edge of an advancing contact line is of vanishing physical size, it is expected that phenomena controlling wetting kinetics are atomic scale in nature. In my work, molecular dynamics simulations on metallic Pb-Cu systems were performed to study the early stage spreading. A counterintuitive result from our MD simulations is that even nanometer scale metallic drops exhibit a regime of wetting that is dictated by inertial effects. Therefore, mechanisms observed in atomic simulations may provide insight to corresponding mechanisms for inertial regime spreading of macro-scale droplets. We introduce a Tolman length corrected surface tension to account for liquid/vapor interface curvature effects that manifest in small drops. In addition, for inertial spreading on low advancing contact angle surface, a second nanoscale effect is observed which is unique to this surface and related to curvature gradients along a significant portion of the liquid/vapor interface. After accounting for all the nanoscale size effects, data from inertial spreading of nanodrops could be well described by continuum inertial wetting theory.
520 $a Additionally, we explore the fundamental mechanisms in controlling the rapid contact line advancement during the inertial spreading. It is demonstrated that high contact line velocity is abetted by structural ordering of a liquid layer adjacent to the solid. Meanwhile, a tensile strain in this layer, which is most pronounced nearest to the contact line, may also play a role.
520 $a For the second interest of my dissertation, wetting and spreading of nano-suspension drops are investigated using the same metallic system. The concept of assembling ordered arrays of nanoparticles on a substrate surface via suspension droplet wetting and subsequent evaporation has fueled a large body of research in this area. Self-pinning is a phenomenon intrinsic to the advancement or retraction of liquid/solid/vapor three-phase contact lines for nano-fluid droplets; in such cases, particles entrained to the contact line halt its motion, preventing the system from reaching equilibrium. Depending on the desired application, this can be either detrimental (e.g. preventing complete coating of a substrate by the suspension) or beneficial (e.g. stabilizing non-equilibrium droplet morphologies). Another relevant phenomenon is de-pinning, where an initially halted contact line is able to separate from the pinning particle and continue its advance (or retraction) across the surface. While deterministic engineering of nanoparticle distribution requires thorough understanding of the thermodynamics and associated wetting kinetics of nanosuspension droplets, quantitative understanding of forces acting on suspended nanoparticles is needed; however, such measurements remain experimentally inaccessible. Herein, we present results from molecular dynamics simulations of nanosuspension droplets spreading on solid surfaces, with emphasis on revealing forces on suspended particles. (Abstract shortened by ProQuest.).
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Mechanical engineering. $3 557493
650 4 $a Engineering. $3 561152
655 7 $a Electronic books. $2 local $3 554714
690 $a 0548
690 $a 0537
710 2 $a ProQuest Information and Learning Co. $3 1178819
710 2 $a Lehigh University. $b Mechanical Engineering. $3 845623
773 0 $t Dissertation Abstracts International $g 78-10B(E).
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=10282807 $z click for full text (PQDT)