共查询到20条相似文献,搜索用时 31 毫秒
1.
提出一种扩展或收缩气/液界面单分子层的分子密度,用荧光成像技术检测单分子层的扩展或收缩效果的新方法——垂悬液滴分析方法-此方法通过改变液滴体积,对液滴界面上的表面活性剂分子实施扩展和收缩,具有Langmuir-Blodgett(LB槽)的功能-对表面活性剂荧光分子,用液滴的激光感生荧光图像,可以实时测量液滴界面的相对分子密度变化;用偏振荧光分析技术,可获取荧光偶极矩在液滴界面的相对取向-对罗丹明(B)表面活性剂分子ODRB的实验结果表明:1) 表面单分子层分子密度在压缩过程中遵循σ/σ0关键词: 相似文献
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本文用电子束感生电流像方法对Hg_(0.8)Cd_(0.2)Te光伏探测器量子效率在光敏面上的分布进行了测量,表明量子效率分布是不均匀的,在光敏面的边缘呈下降趋势,与用激光外差接收方法获得的实验结果一致.对产生量子效率下降的原因进行了初步探讨. 相似文献
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A new laser shadowgraphy method is presented to measure the dynamic contact angle of a sessile drop on a nontransparent metal substrate and simultaneously visualize flow motions inside the drop. A collimated laser beam is refracted into the drop, then reflected on the substrate surface and finally refracted out of the drop to form a shadowgraphic image on a screen. The instant diameters of the refracted-shadowgraphic image, cooperated with the corresponding instant contact-diameters of the drop measured from the magnified top view, are used to determine the instant contact angles of the sessile drop. At the same time, flow motions, if any, in the drop can be visualized from the refracted-shadowgraphic image. The new method is demonstrated to be a very simple, accurate, and unique optical technique for simultaneous measuring of the dynamic contact angle of a liquid drop spreading on a nontransparent metal substrate with flow visualization in the drop. 相似文献
4.
Three-dimensional multi-relaxation-time lattice Boltzmann front-tracking method for two-phase flow 下载免费PDF全文
We developed a three-dimensional multi-relaxation-time lattice Boltzmann method for incompressible and immiscible two-phase flow by coupling with a front-tracking technique. The flow field was simulated by using an Eulerian grid, an adaptive unstructured triangular Lagrangian grid was applied to track explicitly the motion of the two-fluid interface, and an indicator function was introduced to update accurately the fluid properties. The surface tension was computed directly on a triangular Lagrangian grid, and then the surface tension was distributed to the background Eulerian grid. Three benchmarks of two-phase flow, including the Laplace law for a stationary drop, the oscillation of a three-dimensional ellipsoidal drop,and the drop deformation in a shear flow, were simulated to validate the present model. 相似文献
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A method for processing the results of dynamic spall fracture tests, based on the exact solution of the wave equation, and its commonly used simplified version based on the assumed unique relation between the free surface velocity drop and the ultimate medium fracture stress, are analyzed. Using the considered exact solutions of the wave technique, tensile stress pulses during spalling are determined. The obtained stress levels at the fracture point are compared with the spall strength calculated by the velocity drop technique. The cases of agreement and disagreement of the results obtained using both techniques are shown. By the example of differently shaped loading pulses, possible scenarios of sample fracture are presented, in particular, the probability of the fracture delay effect is shown, which can be lost in the simplified processing method. 相似文献
7.
N. E. Galaktionova E. V. Galaktionov E. A. Tropp 《Bulletin of the Russian Academy of Sciences: Physics》2009,73(10):1315-1319
The variational formulation of general problems of capillary surface equilibrium (problems on a drop on a solid surface, drop
on the surface of a drop of another liquid, partly faceted capillary surface) is considered. For the problem of a partly faceted
capillary surface, the Legendre transformation between the equilibrium form and surface energy density is used. 相似文献
8.
本文提出了一种核梯度改进光滑粒子动力学(KGC-SPH)方法,模拟了黏性液滴形变自由表面问题.首先,通过模拟等温黏性液滴拉伸和旋转变形,验证了KGC-SPH法较SPH法具有较高精度和更好稳定性,且能很好地保持总角动量守恒.其次,基于非等温van der Waals模型对平衡态圆形液滴的形成过程进行数值研究,观察到小幅度振荡现象,并给出了一种新的克服张力不稳定性的方法和一种适合KGC-SPH方法的新的表面张力处理技术.最后,研究了van der Waals液滴的周期性振荡现象,讨论了初始椭圆形液滴长短半轴比
关键词:
光滑粒子动力学
黏性液滴
van der Waals模型
表面张力 相似文献
9.
An image analysis technique has been developed in order to determine the drop size distributions of sprays produced by low‐velocity plain cylindrical jets. The particle sizing method is based on incoherent backlight images. Each drop is analyzed individually in the image. The two‐dimensional image resulting from the projection of the three‐dimensional object shape (the drop) on a screen (the video sensor surface) is modeled. The model, based on the point spread function formulation, has been developed to derive a relation between contrast and relative width of individual drops. This relation is used to extend the domain of validity of drop size in terms of size range, out of focus and image resolution. The shape parameter is determined for each drop image through morphological analysis. Spherical and non‐spherical droplets are then sorted on the basis of this parameter. Non‐spherical drops are regarded as non‐fully atomized liquid bulks or coalesced drops. Finally, the droplet size distribution of true spherical droplets is established for a low‐velocity plain cylindrical liquid jet. 相似文献
10.
Wettability of glass/epoxy and carbon/epoxy composites materials has been determined via sessile drop technique. Good-Van Oss approach has been used to evaluate surface free energy parameters of smooth and rough surfaces. Results obtained point out the influence of fibre reinforcement on surface free energy of composite materials. In addition, the interest of surface treatment to increase surface roughness has been discussed in terms of wettability. To sum up, results obtained clearly demonstrate the necessity of considering properties of a given composite surface not only as a polymer but a fibre/polymer couple. The drawn conclusions are of great interest as it may have numerous consequences in applications such as adhesion. 相似文献
11.
An exact solution is obtained to the problem of axisymmetric normal modes and natural frequencies characterizing surface perturbations
of a drop that sits with an arbitrary wetting angle on a substrate and experiences only gravity and surface tension. The resulting
mode solutions are used to calculate and analyze different shapes of the perturbed surface for the same drop placed on a vibrating
base. The distinctive feature of the present study is the explicit representation of the results in the form of calculated
shapes of the surface of a vibrating drop, comparison of the parameters of actual drops with resonance frequencies, and comparison
with experimental data. 相似文献
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The effect of nitrogen ion implantation on the nanomechanical properties of single crystal Si was evaluated by means of a conventional Vickers indentation and nanoindentation tests. The images of Si surfaces before and after nitrogen implantation were observed and their average surface roughnesses were measured by an atomic force microscope (AFM), while the changes in the morphology and microstructure of the single crystal Si by N implantation were examined by field emission scanning electron microscope (SEM) and X-ray diffractometer (XRD). In addition, the hydrophilic/hydrophobic surface property of the N-doping Si film was determined from the measurement of water contact angle by the sessile drop technique. Furthermore, the effects of the doping energy on the surface contact angle and the surface roughness and the Vickers hardness of the film are also investigated. 相似文献
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S. Residori E. Pampaloni P.K. Buah-Bassuah F.T. Arecchi 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,15(2):331-334
As a drop of fluid is deposited on the surface of a miscible fluid (that we call the solvent), it undergoes a strong pulling
due to its surface rupture and it acquires a kinetic energy independently of gravity. For the drop and the solvent being of
the same fluid we observe a drop injection at an initial velocity which scales as the square root of the surface tension of
the drop against air. Once injected, the drop develops a transverse instability giving rise to an expanding ring. Viscosity
terminates the process and stops the ring. We show that the final ring height follows a scaling law whereas two asymptotical
scaling regimes can be identified for the ring radius.
Received 31 August 1999 相似文献
16.
重力场中竖壁上水滴界面形状热力学平衡的稳定性分析 总被引:5,自引:2,他引:3
1前言水蒸汽在冷壁面上的冷凝方式有两种:膜状冷凝和滴状冷凝。由于工业生产的需要,对现行工业用冷凝器中膜状冷凝的研究,从理论模式到实际设计计算都已经达到相当完善的程度。滴状冷凝较之膜状冷凝是一种高效的换热方式,从1930年Schmidtetal发现这种高效的换热方式以来,半个多世纪中进行过大量的研究工作。但由于滴状冷凝过程的复杂性,从理论模式的建立到工业化应用都没有取得实质性进展。本文在文献[1]的基础上继续从热力学观点,分析在重力作用下,疏水性竖壁上生成的水滴界面形状的热力学平衡稳定性,建立了相… 相似文献
17.
Ultrasmall lysozyme microcrystals are grown by classical hanging‐drop vapor diffusion and by its modification using a homologous protein thin‐film template displaying long‐range order. The nucleation and growth mechanisms of lysozyme microcrystals are studied at the thin lysozyme film surface using a new in situµGISAXS (microbeam grazing‐incidence small‐angle X‐ray scattering) technique recently developed at the microfocus beamline of the ESRF in Grenoble, France. New insight on the nucleation and crystallization processes appear to emerge. 相似文献
18.
《中国物理 B》2015,(10)
We show experimentally that when an unfocused continuous wave(CW) laser beam is obliquely incident onto the surface of a millimeter-sized mineral oil drop on sucrose solution, it will exert a pushing force on the oil drop, making it move forwards along the surface of the sucrose solution. However, after a period of time, the oil drop stops moving. This can be explained as the phenomenon caused by the change of Abraham momentum, the optical gradient force, and friction together. 相似文献
19.
Daniel Sindayihebura Jean Cousin Christophe Dumouchel 《Particle & Particle Systems Characterization》1997,14(2):93-101
The atomisation of liquids by means of low-frequency ultrasonic atomisers results from unstable surface waves generated on the free surface of a thin liquid film. These unstable waves are obtained from the tuning of the amplitude and the frequency of an imposed oscillation. The thin liquid film develops as the liquid spreads over the atomising surface of the atomiser. This paper focuses on a systematic experimental analysis of the sprays produced by low-frequency ultrasonic atomisers. The thickness of the liquid film was measured and its effects on the drop diameter were studied together with the effects of both the liquid's physical properties and the ultrasonic atomiser's characteristics. The relationship between the mean drop diameter and the surface wave wavelength was accurately determined and introduced into a mathematical approach based on the maximum entropy formalism to predict the drop size distribution of the spray. Within the range of working conditions tested, the application of this formalism is successful and provides a procedure for the prediction of spray drop size distributions from calculations only. 相似文献
20.
G. Yu. Yalamov 《Technical Physics》2004,49(2):183-187
A new theory of diffusiophoresis of large volatile spherical aerosol drops that is an extension of investigations [1–8] is developed. The influence of the radius of the drop, the surface tension coefficient varying over the surface of the drop, the evaporation coefficient α of the liquid, and the flows inside the drop on the diffusiophoresis rate are taken into account. Expressions obtained allow for direct determination of the velocity of large individual aerosol drops in a binary gas mixture nonuniform in component concentration. It is shown that both the magnitude and the direction of the diffusiophoresis velocity depend on α and the size of the drop. It is assumed that the size of the drop varies but remains considerably greater than the mean free path of gas molecules. 相似文献