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Theoretical study of the effect of probe shape on adhesion force between probe and substrate in atomic force microscope experiment

Yang L., Hu J., Kong L.

Journal of Theoretical and Applied Mechanics

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2015

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Vol. 53 nr 1

235--241

EN

The quantitative description of adhesion force dependence on the probe shapes are of importance in many scientific and industrial fields. In order to elucidate how the adhesion force varied with the probe shape in atomic force microscope manipulation experiment, we performed a theoretical study of the influences of the probe shape (the sphere and parabolic probe) on the adhesion force at different humidity. We found that the combined action of the triple point and the Kelvin radius guiding the trend of the adhesion force, and these two fundamental parameters are closely related to the probe shape. Whilst, the theoretical results demonstrate that the adhesion force is in good agreement with the experiment data if the van der Waals force is taken into account.

2

Rupture of an evaporating liquid bridge between two grains

Mielniczuk B., El Youssoufi M. S., Sabatier L., Hueckel T.

Acta Geophysica

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2014

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Vol. 62, no. 5

1087--1108

EN

The study examines rupture of evaporating liquid bridges between two glass spheres. Evolution of the bridge profile has been recorded with the use of high-speed camera. Geometrical characteristics of the bridge were then used to calculate evolution of the variables during the process: Laplace pressure, capillary force, and surface tension force. For the purpose of reference, the bridge evolution is followed also during kinematic extension. During both processes the diameter of the neck decreases, with an acceleration of about 1-2 ms before the rupture. Two distinct rupture modes are observed, depending on the bridge aspect ratio. After the rupture, the mass of liquid splits, forming two separate oscillating drops attached to the spheres, and a suspended satellite droplet. Just before the rupture, an increasing repulsive Laplace pressure, and decreasing negative surface tension force develop. Capillary force follows the trend of the surface tension force, with an accelerating decline. Duration of the whole process and liquid mass stabilization is from 10 to 60 ms.

3

Higher Orders Instability of a Hollow Jet Endowed with Surface Tension

Radwan A. E., Ahmed N. A.

Mechanics and Mechanical Engineering

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2008

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Vol. 12, nr 1

69-77

EN

The higher orders instability of a gas cylinder ambient with an incompressible inviscid liquid endowed with surface tension is analyzed. The perturbation equations up to third order are derived and solved. The surface displacements, the velocity potentials and the dispersion relations are derived for each order of axisymmetric perturbation. It is found that, up to third order, a transition from instability to stability states occurs when the perturbed wavelength equals the circumference of the gas cylinder. The stability discussions for the present model have been done and for the nonhollow jet as well. The hollow jet instability is much larger than that of the nonhollow model. It is found that the maximum temporal amplification prevailing in the hollow jet is much higher than that of the full fluid jet. These results are consistent with some data of the experimental work of Kendall [9], in the first order perturbation.

4

Stability of Compressible Magnetized Hollow Cylinder Pervaded by Azimuthally Field

Radwan A. E.

Mechanics and Mechanical Engineering

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2007

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Vol. 11, nr 1

87-96

EN

The stability of compressible magnetized hollow cylinder (gas jet embedded into a liquid) pervaded by varying azimuthally magnetic field has been developed for all symmetric m = 0 and asymmetric m ≠ 0 pertubation modes (m transverse wavenumber). The problem is formulated well, apart from the singular solutions the different variables are determined, the stability criterion is derived and discussed. The axial field in the liquid region is stabilizing for all short and long wavelengths and that effect is independent of m values. In contrast, the azimuthal field in the gas is destabilizing or not according to restrictions and m values. The capillary force along the gas { liquid interface is destabilizing only for m = 0, for small longitudinal wavenumber and stabilizing in the rest. The compressibility has a strong stabilizing effect for all m ≥ 0 disturbance modes. Here the instability due to azimuthal field and the capillary force could be completely suppressed under restrictions and stability sets in.