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T.d. Blake - One of the best experts on this subject based on the ideXlab platform.
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The temperature-dependence of the Dynamic Contact Angle
Journal of colloid and interface science, 2019Co-Authors: T.d. Blake, G.n. BattsAbstract:Abstract Hypothesis The wetting of a solid by a liquid is a thermally-activated molecular rate process, which may be investigated by studying the temperature-dependence of the Dynamic Contact Angle at standard experimental scales. Experiments We use the plunging-tape method and a low-powered microscope to measure the Dynamic Contact Angle of di-n-butyl phthalate (DBP) on poly(ethylene terephthalate) (PET) tape over a very wide speed range of 0.003–100 cm/s at 5 temperatures from 15 °C to 55 °C. The molecular-kinetic theory of Dynamic wetting (the MKT) is then used to interpret the data, which span Angles from 8° to near 180°. Findings The MKT successfully accounts for the temperature-dependence of the Dynamic Contact Angle, yielding rational values for key parameters including the activation free energy of wetting. Arrhenius-like behavior is also demonstrated. These results would appear to confirm that, at the molecular-scale, Dynamic wetting is a thermally-activated rate process and that the influence of temperature is not restricted simply to its effect on surface tension and viscosity. The data show a discontinuity at Dynamic Contact Angles between 60° and 90° that implies a velocity-dependent change in the wetting mechanism. We attribute this to the chemical heterogeneity of the PET surface, which contains both polar and non-polar groups. The parameters obtained by applying the MKT suggest that the interactions of DBP with these groups determine, respectively, the Dynamics observed below and above the transition. The sum of the activation free energies of wetting on either side of the transition is close to the total thermoDynamic work of adhesion of DBP to PET.
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nonlocal hydroDynamic influence on the Dynamic Contact Angle slip models versus experiment
Physical Review E, 2006Co-Authors: M C T Wilson, Yulii D. Shikhmurzaev, A. Clarke, J L Summers, T.d. BlakeAbstract:Experiments reported by Blake et al. [Phys. Fluids., 11, 1995 (1999)] suggest that the Dynamic Contact Angle formed between the free surface of a liquid and a moving solid boundary at a fixed Contact-line speed depends on the flow field and geometry near the moving Contact line. We examine quantitatively whether or not it is possible to attribute this effect to the bending of the free surface due to hydroDynamic stresses acting upon it and hence interpret the results in terms of the so-called ``apparent'' Contact Angle. It is shown that this is not the case. Numerical analysis of the problem demonstrates that, at the spatial resolution reported in the experiments, the variations of the ``apparent'' Contact Angle (defined in two different ways) caused by variations in the flow field, at a fixed Contact-line speed, are too small to account for the observed effect. The results clearly indicate that the actual (macroscopic) Dynamic Contact Angle\char22{}i.e., the one used in fluid mechanics as a boundary condition for the equation determining the free surface shape\char22{}must be regarded as dependent not only on the Contact-line speed but also on the flow field and geometry in the vicinity of the moving Contact line.
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Influence of the Dynamic Contact Angle on the characterization of porous media
Journal of colloid and interface science, 2003Co-Authors: G Martic, J. De Coninck, T.d. BlakeAbstract:It has been shown recently that the classical Lucas-Washburn equation, often used to model the Dynamics of liquid penetration into porous media, should be modified to take account of the Dynamic Contact Angle between the liquid and the pore. Here we show how neglect of this effect can lead to significant errors in estimation of the effective pore radius.
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Experimental evidence of nonlocal hydroDynamic influence on the Dynamic Contact Angle
Physics of Fluids, 1999Co-Authors: T.d. Blake, M. Bracke, Yulii D. ShikhmurzaevAbstract:The Dynamic Contact Angle formed when a liquid curtain impinges onto a moving solid is measured for aqueous glycerol solutions in different flow regimes. It is usually assumed that the Dynamic Contact Angle is simply a function of the Contact-line speed and the material properties of the Contacting media. The new results show that this is not the case. For a given gas/liquid/solid combination and a given Contact-line speed, the Dynamic Contact Angle can be varied by varying the flow rate of the liquid and/or the curtain height, that is by varying the flow field near the Contact line. The possibility of attributing this effect merely to free-surface bending and interpreting the results in terms of the so-called “apparent” Contact Angle is discussed and ruled out on the basis of some general qualitative arguments and analysis of the characteristic length scales involved. A probable connection between the observed effect and the physical mechanism of interface disappearance and formation incorporated in a recently developed theory of wetting is discussed.
Pirouz H Kavehpour - One of the best experts on this subject based on the ideXlab platform.
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effect of viscous force on Dynamic Contact Angle measurement using wilhelmy plate method
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2018Co-Authors: Alireza Mohammad Karim, Pirouz H KavehpourAbstract:Abstract Wilhelmy plate method does not consider viscous force in the force balance equation to measure the Dynamic Contact Angle and this results in a significant error in the measurement. Differences between the results obtained by optical method and Wilhelmy plate method indicate the importance of viscous force in the force balance equation. A theoretical viscous model is proposed, which must be considered in the force balance equation in Wilhelmy plate method to increase the accuracy of the Dynamic Contact Angle measurement, especially for the case of highly viscous liquids and for experiments at large speeds of the plate, which can lead to large shear rate along the surface of the plate.
Z. M. Zorin - One of the best experts on this subject based on the ideXlab platform.
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Surface Tension and Dynamic Contact Angle of Water in Thin Quartz Capillaries.
Journal of colloid and interface science, 2000Co-Authors: V.d. Sobolev, N. V. Churaev, Manuel G. Velarde, Z. M. ZorinAbstract:Abstract The surface tension of water has been measured in quartz capillaries with radii from 200 down to 40 nm. It appears that the surface tension does not differ from the known (bulk) values in the temperature range from 8 to 70°C, within 1% experimental error. The Dynamic Contact Angle, θ d , vanishes when the capillary surface is covered with a wetting film left behind the receding meniscus. In the case of a dry surface, θ d depends on the velocity of the meniscus motion. The results obtained do not agree with presently available theoretical predictions from hydroDynamic theories of Dynamic Contact Angles. Rather the kinetics of water vapor adsorption ahead of the moving meniscus seems to be the major controlling agent of the Dynamic Contact Angle.
Jiuyu Zhao - One of the best experts on this subject based on the ideXlab platform.
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Mathematical model of liquid spontaneous imbibition into gas-saturated porous media with Dynamic Contact Angle and gravity
Chemical Engineering Science, 2021Co-Authors: Fuyong Wang, Jiuyu ZhaoAbstract:Abstract Liquid imbibition with Dynamic Contact Angle is a ubiquitous phenomenon of fluid flow in porous media, but its analytical solution is challenging to derive. In this work, the analytical solution of liquid imbibition in an inclined capillary tube with velocity-dependent Contact Angle and gravity is first derived. The time required for the liquid-gas interface to reach a certain distance by spontaneous imbibition with static Contact Angle and Dynamic Contact Angle are provided. Assuming that the porous medium consists of a bundle of tortuous capillary tubes with fractal distribution of pore size, a mathematical model of liquid imbibition in core-scale porous media with Dynamic Contact Angle and gravity is developed. The studies show that the Dynamic Contact Angle can significantly reduce the imbibition velocity at the initial stage of imbibition, especially in large pores, which forms a nonlinear correlation between imbibition velocity and imbibition time in a log-log plot.
Tao Liu - One of the best experts on this subject based on the ideXlab platform.
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spontaneous imbibition in fractal tortuous micro nano pores considering Dynamic Contact Angle and slip effect phase portrait analysis and analytical solutions
Scientific Reports, 2018Co-Authors: Yinghao Shen, Yanjun Zhang, Tao LiuAbstract:Shales have abundant micro-nano pores. Meanwhile, a considerable amount of fracturing liquid is imbibed spontaneously in the hydraulic fracturing process. The spontaneous imbibition in tortuous micro-nano pores is special to shale, and Dynamic Contact Angle and slippage are two important characteristics. In this work, we mainly investigate spontaneous imbibition considering Dynamic Contact Angle and slip effect in fractal tortuous capillaries. We introduce phase portrait analysis to analyse the Dynamic state and stability of imbibition. Moreover, analytical solutions to the imbibition equation are derived under special situations, and the solutions are verified by published data. Finally, we discuss the influences of slip length, Dynamic Contact Angle and gravity on spontaneous imbibition. The analysis shows that phase portrait is an ideal tool for analysing spontaneous imbibition because it can evaluate the process without solving the complex governing ordinary differential equations. Moreover, Dynamic Contact Angle and slip effect play an important role in fluid imbibition in fractal tortuous capillaries. Neglecting slip effect in micro-nano pores apparently underestimates imbibition capability, and ignoring variations in Contact Angle causes inaccuracy in predicting imbibition speed at the initial stage of the process. Finally, gravity is one of the factors that control the stabilisation of the imbibition process.
