The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Zijing Ding - One of the best experts on this subject based on the ideXlab platform.
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breakup of ultra Thin Liquid Films on vertical fiber enhanced by marangoni effect
Chemical Engineering Science, 2019Co-Authors: Zijing Ding, Zhou Liu, Rong Liu, Chun YangAbstract:Abstract An ultra-Thin Liquid Film flowing down a vertical uniformly heated cylinder under the influence of gravity is investigated. A Thin Liquid Film model is derived, assuming that the Film thickness h is much smaller than the fiber radius a. To predict the breakup of Film, the van der Waals attraction, proportional to h - 3 , is taken into account. Linear stability analysis shows that the Rayleigh-Plateau instability is enhanced by the long-range attractions and Marangoni effect. The spatial-temporal stability analysis shows that the instability is absolute when A + M > 0.17 (A is a composite Hamaker number accounting for the strength of van der Waals attractions and M is the Marangoni number). A self-similarity analysis shows that the Film Thins as h ∼ ( t r - t ) 1 / 5 ( t r is the breakup time), which is supported by the numerical simulations of the Thin Film model. Although the scaling is independent on the Marangoni effect, nonlinear simulations demonstrate that the breakup time t r decreases as the Marangoni effect becomes stronger, demonstrating that the breakup process is accelerated by the Marangoni effect. Nonlinear simulation also shows that the Thin heated or non-heated Film mainly breaks up in the absolutely unstable regime.
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Thermocapillary Thin-Film flows on a compliant substrate.
Physical Review E, 2019Co-Authors: Youchuang Chao, Zijing DingAbstract:We study the dynamics of a Thin Liquid Film on a compliant substrate in the presence of thermocapillary effect. A set of long-wave equations are derived to investigate the effects of fluid gravity (G), fluid inertia (Re), and Marangoni stresses (Ma) on the dynamics of the Liquid Film and the compliant substrate. By performing linear stability analysis and time-dependent computations of the long-wave equations, we examine two different cases: Thin-Film flows on a horizontally compliant substrate (β=0, where β is the inclined angle) and down a vertically compliant substrate (β=π/2), respectively. For β=0, we neglect fluid inertia and identify two different modes: (1) sinuous mode, where the deformations of Liquid-air and Liquid-substrate interfaces are in phase, which is induced by the fluid gravity, and (2) varicose mode, where the deformations of two interfaces are in phase opposition, which is induced by the Marangoni stresses. For β=π/2, we consider a weak fluid inertia and only observe the varicose mode driven by fluid inertia and Marangoni stresses. However, because the gravity direction is parallel to the substrate, the fluid gravity modifies the varicose mode, making the deformations of two interfaces out of phase. In particular, we also seek the nonlinear traveling-wave solutions in the case of β=π/2, revealing that fluid inertia and/or heating effect enhance the height and speed of the traveling waves. In both cases, the introduction of a strong wall heating gives rise to large deformations of both the Thin Liquid Film and the compliant substrate.
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thermocapillary Thin Film flows on a compliant substrate
Physical Review E, 2019Co-Authors: Youchuang Chao, Zijing DingAbstract:We study the dynamics of a Thin Liquid Film on a compliant substrate in the presence of thermocapillary effect. A set of long-wave equations are derived to investigate the effects of fluid gravity $(G)$, fluid inertia (Re), and Marangoni stresses (Ma) on the dynamics of the Liquid Film and the compliant substrate. By performing linear stability analysis and time-dependent computations of the long-wave equations, we examine two different cases: Thin-Film flows on a horizontally compliant substrate $(\ensuremath{\beta}=0$, where $\ensuremath{\beta}$ is the inclined angle) and down a vertically compliant substrate $(\ensuremath{\beta}=\ensuremath{\pi}/2)$, respectively. For $\ensuremath{\beta}=0$, we neglect fluid inertia and identify two different modes: (1) sinuous mode, where the deformations of Liquid-air and Liquid-substrate interfaces are in phase, which is induced by the fluid gravity, and (2) varicose mode, where the deformations of two interfaces are in phase opposition, which is induced by the Marangoni stresses. For $\ensuremath{\beta}=\ensuremath{\pi}/2$, we consider a weak fluid inertia and only observe the varicose mode driven by fluid inertia and Marangoni stresses. However, because the gravity direction is parallel to the substrate, the fluid gravity modifies the varicose mode, making the deformations of two interfaces out of phase. In particular, we also seek the nonlinear traveling-wave solutions in the case of $\ensuremath{\beta}=\ensuremath{\pi}/2$, revealing that fluid inertia and/or heating effect enhance the height and speed of the traveling waves. In both cases, the introduction of a strong wall heating gives rise to large deformations of both the Thin Liquid Film and the compliant substrate.
Ruth E Baltus - One of the best experts on this subject based on the ideXlab platform.
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regular solution theory for low pressure carbon dioxide solubility in room temperature ionic Liquids ionic Liquid solubility parameter from activation energy of viscosity
Industrial & Engineering Chemistry Research, 2010Co-Authors: Surya S Moganty, Ruth E BaltusAbstract:The low pressure solubility of carbon dioxide in eight commercially available room temperature ionic Liquids was measured at 10, 25, and 40 °C using a transient Thin Liquid Film technique. In this paper, carbon dioxide solubility is reported as the Henry’s law constant for each system. Experimental results were interpreted using regular solution theory where Eyring’s reaction rate theory was successfully applied to estimate the solubility parameter of each ionic Liquid from its activation energy of viscosity. Consistent with the regular solution theory, the carbon dioxide solubility was found to be inversely proportional to the solubility parameter of the ionic Liquid, and Henry’s law constants were successfully correlated with the square of the difference between ionic Liquid and carbon dioxide solubility parameters.
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experimental measurement of the solubility and diffusivity of co2 in room temperature ionic Liquids using a transient Thin Liquid Film method
Industrial & Engineering Chemistry Research, 2007Co-Authors: Ying Hou, Ruth E BaltusAbstract:In this paper, results from an experimental investigation of carbon dioxide (CO2) solubility and diffusivity in the ionic Liquids 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([bmim][Tf2N]), 1,2-dimethyl-3-propylimidazolium bis(trifluoromethylsulfonyl)imide ([pmmim][Tf2N]), 1-butyl-3-methylpyridinium bis(trifluoromethyl sulfonyl)imide ([bmpy][Tf2N]), 1-(3,4,5,6-perfluorohexyl)-3-methylimdazolium bis(trifluoromethyl sulfonyl)imide ([perfluoro-hmim][Tf2N]), and 1-n-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) are reported. A transient Thin Liquid Film method was developed, which enables one to determine the Henry's law constant and the diffusivity at low pressure simultaneously. Measurements were performed at temperatures in the range of 283−323 K. Henry's law constants were in the range of 25.5−84 bar and were in general agreement with measurements reported by other researchers for these and similar ionic Liquids. The entropies and enthalpies of absorption were determined to...
Youchuang Chao - One of the best experts on this subject based on the ideXlab platform.
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Thermocapillary Thin-Film flows on a compliant substrate.
Physical Review E, 2019Co-Authors: Youchuang Chao, Zijing DingAbstract:We study the dynamics of a Thin Liquid Film on a compliant substrate in the presence of thermocapillary effect. A set of long-wave equations are derived to investigate the effects of fluid gravity (G), fluid inertia (Re), and Marangoni stresses (Ma) on the dynamics of the Liquid Film and the compliant substrate. By performing linear stability analysis and time-dependent computations of the long-wave equations, we examine two different cases: Thin-Film flows on a horizontally compliant substrate (β=0, where β is the inclined angle) and down a vertically compliant substrate (β=π/2), respectively. For β=0, we neglect fluid inertia and identify two different modes: (1) sinuous mode, where the deformations of Liquid-air and Liquid-substrate interfaces are in phase, which is induced by the fluid gravity, and (2) varicose mode, where the deformations of two interfaces are in phase opposition, which is induced by the Marangoni stresses. For β=π/2, we consider a weak fluid inertia and only observe the varicose mode driven by fluid inertia and Marangoni stresses. However, because the gravity direction is parallel to the substrate, the fluid gravity modifies the varicose mode, making the deformations of two interfaces out of phase. In particular, we also seek the nonlinear traveling-wave solutions in the case of β=π/2, revealing that fluid inertia and/or heating effect enhance the height and speed of the traveling waves. In both cases, the introduction of a strong wall heating gives rise to large deformations of both the Thin Liquid Film and the compliant substrate.
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thermocapillary Thin Film flows on a compliant substrate
Physical Review E, 2019Co-Authors: Youchuang Chao, Zijing DingAbstract:We study the dynamics of a Thin Liquid Film on a compliant substrate in the presence of thermocapillary effect. A set of long-wave equations are derived to investigate the effects of fluid gravity $(G)$, fluid inertia (Re), and Marangoni stresses (Ma) on the dynamics of the Liquid Film and the compliant substrate. By performing linear stability analysis and time-dependent computations of the long-wave equations, we examine two different cases: Thin-Film flows on a horizontally compliant substrate $(\ensuremath{\beta}=0$, where $\ensuremath{\beta}$ is the inclined angle) and down a vertically compliant substrate $(\ensuremath{\beta}=\ensuremath{\pi}/2)$, respectively. For $\ensuremath{\beta}=0$, we neglect fluid inertia and identify two different modes: (1) sinuous mode, where the deformations of Liquid-air and Liquid-substrate interfaces are in phase, which is induced by the fluid gravity, and (2) varicose mode, where the deformations of two interfaces are in phase opposition, which is induced by the Marangoni stresses. For $\ensuremath{\beta}=\ensuremath{\pi}/2$, we consider a weak fluid inertia and only observe the varicose mode driven by fluid inertia and Marangoni stresses. However, because the gravity direction is parallel to the substrate, the fluid gravity modifies the varicose mode, making the deformations of two interfaces out of phase. In particular, we also seek the nonlinear traveling-wave solutions in the case of $\ensuremath{\beta}=\ensuremath{\pi}/2$, revealing that fluid inertia and/or heating effect enhance the height and speed of the traveling waves. In both cases, the introduction of a strong wall heating gives rise to large deformations of both the Thin Liquid Film and the compliant substrate.
Plamen Tchoukov - One of the best experts on this subject based on the ideXlab platform.
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studying demulsification mechanisms of water in crude oil emulsions using a modified Thin Liquid Film technique
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018Co-Authors: Fan Yang, Plamen Tchoukov, Peiqi Qiao, Erica Pensini, Tadeusz Dabros, Jan CzarneckiAbstract:Abstract The Thin Liquid Film (TLF) technique equipped with Scheludko-Exerowa cell has been demonstrated to be a valuable tool for studying stability of dispersed systems of soft matter such as emulsions and foams. Many industrial applications involve the addition of various chemical aids to obtain desired properties or resolve technical problems. One of the examples is the use of chemical demulsifiers to remove emulsified water from petroleum emulsions. To study the role of chemicals in this process, a TLF technique with a dosing system is required to add demulsifiers into already formed Thin Liquid Films stabilized by interfacial layers formed from indigenous surface active molecules. Herein, we present a modified design of the Scheludko-Exerowa cell with a dosing mechanism which allows for addition of desired chemicals to the intervening organic Liquid Film that is already formed. The stability of the water-in-oil emulsions and the mechanisms of their chemical destabilization were studied by determining the Thinning process of intervening Thin oil Films before and after dosing a controlled amount of demulsifiers into the Film. Dosing of a biodegradable polymer demulsifier (EC300) into the intervening oil Film converted a stable Film formed by asphaltene-in-heptol solutions into an unstable Film with lifetimes of less than 20 s. The observed change in the Film drainage rate and stability is related to the disruption of asphaltene network formed at the oil-water interface by EC300 demulsifiers. The experiments with the modified TLF cell also revealed the overdosing effect of EC300 demulsifier, forming more stable Films at high EC300 concentrations. A comparison of the experimental results between a dosed system and a premixed system confirmed the value of the modification in the current TLF technique to study the stabilization/destabilization processes of water-in-oil emulsions that mimic more closely the real petroleum emulsions. The modified TLF technique allows for a better understanding of the underlying demulsification mechanisms.
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effect of approach velocity on Thin Liquid Film drainage between an air bubble and a flat solid surface
Journal of Physical Chemistry C, 2017Co-Authors: Xurui Zhang, Plamen Tchoukov, Rogerio Manica, Zhenghe XuAbstract:The dynamic drainage process of the Liquid Film trapped between an air bubble and a flat silica surface over a wide range of hydrodynamic conditions is studied by a newly developed instrument called integrated Thin Liquid Film force apparatus (ITLFFA) under different salt concentrations. The ITLFFA allows the simultaneous measurement of interaction forces and spatiotemporal Film thickness with accurate control of bubble approach velocity in a large range of Reynolds number from 0.005 to 135. Our study demonstrates that increasing the bubble approach velocity plays a significant role in the hydrodynamic pressure and fluid flow wiThin the draining Film promoting dimple formation and longer drainage time. The drainage time also depends on the competition between the electrical double-layer and van der Waals interactions, which are repulsive in our system, resulting in a flat equilibrium Film at the end. The evolution of the draining Film is analyzed using the Stokes–Reynolds–Young–Laplace (SRYL) model. Compa...
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simultaneous measurement of dynamic force and spatial Thin Film thickness between deformable and solid surfaces by integrated Thin Liquid Film force apparatus
Soft Matter, 2016Co-Authors: Xurui Zhang, Plamen Tchoukov, Rogerio Manica, Louxiang Wang, Qingxia LiuAbstract:Interactions involving deformable surfaces reveal a number of distinguishing physicochemical characteristics that do not exist in interactions between rigid solid surfaces. A unique fully custom-designed instrument, referred to as integrated Thin Liquid Film force apparatus (ITLFFA), was developed to study the interactions between one deformable and one solid surface in Liquid. Incorporating a bimorph force sensor with interferometry, this device allows for the simultaneous measurement of the time-dependent interaction force and the corresponding spatiotemporal Film thickness of the intervening Liquid Film. The ITLFFA possesses the specific feature of conducting measurement under a wide range of hydrodynamic conditions, with a displacement velocity of deformable surfaces ranging from 2 μm s−1 to 50 mm s−1. Equipped with a high speed camera, the results of a bubble interacting with hydrophilic and partially hydrophobic surfaces in aqueous solutions indicated that ITLFFA can provide information on interaction forces and Thin Liquid Film drainage dynamics not only in a stable Film but also in Films of the quick rupture process. The weak interaction force was extracted from a measured Film profile. Because of its well-characterized experimental conditions, ITLFFA permits the accurate and quantitative comparison/validation between measured and calculated interaction forces and temporal Film profiles.
Chi Chuan Hwang - One of the best experts on this subject based on the ideXlab platform.
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nonlinear rupture theory of a Thin Liquid Film on a cylinder
Journal of Colloid and Interface Science, 1996Co-Authors: Jun Liang Chen, Chi Chuan HwangAbstract:The dynamic rupture process of a Thin Liquid Film on a cylinder is investigated numerically. First a nonlinear differential equation that describes the long-wave evolution of the interface shape is derived. After the evolution equation is solved and analyzed, the results reveal that a decrease in the cylinder radius will induce a stronger lateral capillary force and consequently will accelerate the rupture process. Moreover, the tendency of acceleration becomes more explicit in the case of large surface tension.
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effects of inertia on the rupture process of a Thin Liquid Film
Journal of Colloid and Interface Science, 1994Co-Authors: Jun Liang Chen, Chi Chuan HwangAbstract:Abstract The nonlinear evolution equations derived by the integral method are used to study the inertial effect on rupture process of a Thin Liquid Film. The nonlinear numerical results show that inertial effect accelerates the rupture process, and this phenomenon is explicit in the situation of weak effect of van der Waals potential. Finally, we use the perturbation method to obtain the nonlinear solutions which could predict the rupture time approximately.