Lubricant Evaporation and Flow due to Laser Heating With a Skewed Temperature Distribution Induced by Disk Motion

2017 ◽  
Author(s):  
M. Ashraful Haq ◽  
Shao Wang
Keyword(s):  
Surface Tension ◽  
Temperature Distribution ◽  
Approximation Scheme ◽  
Continuous Extension ◽  
Surface Tension Gradient ◽  
Moving Heat Source ◽  
Lubricant Thickness ◽  
Evaporation Surface ◽  
Laser Illumination ◽  
Disk Rotation

Due to the fast disk rotation, the temperature distribution on the disk under laser illumination in heat-assisted magnetic recording (HAMR) tends to deviate significantly from an axisymmetric distribution. A lognormal approximation scheme for the temperature distribution containing a tail based on a fast-moving heat source solution was proposed for use in an equation for the lubricant film involving evaporation, surface tension, disjoining pressure and thin-film enhanced effective viscosity. The results reveal the process of formation of a lubricant trough: an indent of the lubricant profile first forms and grows to a steady-state depth, followed by a continuous extension at the rate of the disk velocity. Both evaporation and thermal capillarity due to the surface tension gradient contribute greatly to the creation of a trough in the lubricant profile while the latter also causes boundary ridges. Unlike the Gaussian temperature-based solution, the local minimum of the lubricant thickness occurs at the trailing edge of the thermal spot.

Breakdown of Evaporating Falling Films as a Function of Surface Tension Gradient

1996 ◽  
Vol 17 (4) ◽  
pp. 72-81 ◽  
Author(s):  
ALI G. BUDIMAN ◽  
C. FLORIJANTO ◽  
J. W. PALEN
Keyword(s):  
Surface Tension ◽  
Surface Tension Gradient ◽  
Falling Films

scholarly journals Effect of a surface tension gradient on the slip flow along a superhydrophobic air-water interface

2018 ◽  
Vol 3 (3) ◽  
Author(s):  
Dong Song ◽  
Baowei Song ◽  
Haibao Hu ◽  
Xiaosong Du ◽  
Peng Du ◽  
...  
Keyword(s):  
Surface Tension ◽  
Slip Flow ◽  
Surface Tension Gradient ◽  
Water Interface ◽  
Air Water Interface

Numerical Simulation of Oil-Droplet Cleavage by Surfactant

1996 ◽  
Vol 118 (2) ◽  
pp. 201-209 ◽  
Author(s):  
Xiaoyi He ◽  
Micah Dembo
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Surface Tension ◽  
Large Deformation ◽  
Concentration Gradient ◽  
Surface Tension Gradient ◽  
Oil Droplets ◽  
Numerical Computations ◽  
Oil Droplet ◽  
Pure Surface

We present numerical computations of the deformation of an oil-droplet under the influence of a surface tension gradient generated by the surfactant released at the poles (the Greenspan experiment). We find this deformation to be very small under the pure surface tension gradient. To explain the large deformation of oil droplets observed in Greenspan’s experiments, we propose the existence of a phoretic force generated by the concentration gradient of the surfactant. We show that this hypothesis successfully explains the available experimental data and we propose some further tests.

scholarly journals Tackling the Short-Lived Marangoni Motion Using a Supramolecular Strategy

CCS Chemistry ◽  
2019 ◽  
Vol 1 (2) ◽  
pp. 148-155 ◽  
Author(s):  
Mengjiao Cheng ◽  
Dequn Zhang ◽  
Shu Zhang ◽  
Zuankai Wang ◽  
Feng Shi
Keyword(s):  
Surface Tension ◽  
Electricity Generation ◽  
Adsorption Equilibrium ◽  
Molecular Level ◽  
Surface Tension Gradient ◽  
Aggregation State ◽  
Physical Limit ◽  
Competitive Kinetics ◽  
Air Liquid Interface ◽  
Spontaneous Motion

Inspired by the intriguing capability of beetles to quickly slide on water, scientists have long translated this surface-tension-gradient–dominated Marangoni motion into various applications, for example, self-propulsion. However, this classical spontaneous motion is limited by a short lifetime due to the loss of the surface tension gradient. Indeed, the propellant of amphiphilic surfactants can rapidly reach an adsorption equilibrium and an excessive aggregation state at the air/liquid interface. Here, we demonstrate a supramolecular host–guest chemistry strategy that allows the breaking of the physical limit of the adsorption equilibrium and the simultaneous removal of surfactant molecules from the interface. By balancing the competitive kinetics between the two processes, we have prolonged the lifetime of the motion 40-fold. Our work presents an important advance in the query of long-lived self-propulsion transport through flexible interference at the molecular level and holds promise in electricity generation applications .

scholarly journals Marangoni Convection of Dust Particles in the Boundary Layer of Maxwell Nanofluids with Varying Surface Tension and Viscosity

Coatings ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1072
Author(s):  
Khaled S. AlQdah ◽  
Naseer M. Khan ◽  
Habib Ben Bacha ◽  
Jae-Dong Chung ◽  
Nehad Ali Shah
Keyword(s):  
Surface Tension ◽  
Nusselt Number ◽  
Temperature Distribution ◽  
Dust Particles ◽  
Physical Parameters ◽  
Temperature Dependent Viscosity ◽  
Liquid Phases ◽  
Variable Surface ◽  
Basic Equations ◽  
Dependent Viscosity

The flow of nanofluids is very important in industrial refrigeration systems. The operation of nuclear reactors and the cooling of the entire installation to improve safety and economics are entirely dependent on the application of nanofluids in water. Therefore, a model of Maxwell’s dusty nanofluid with temperature-dependent viscosity, surface suction and variable surface tension under the action of solar radiation is established. The basic equations of momentum and temperature of the dust and liquid phases are solved numerically using the MATLAB bvp4c scheme. In the current evaluation, taking into account variable surface tension and varying viscosity, the effect of dust particles is studied by immersing dust particles in a nanofluid. Qualitative and quantitative discussions are provided to focus on the effect of physical parameters on mass and heat transfer. The propagation results show that this mixing effect can significantly increase the thermal conductivity of nanofluids. With small changes in the surface tension parameters, a stronger drop in the temperature distribution is observed. The suction can significantly reduce the temperature distribution of the liquid and dust phases. The stretchability of the sheet is more conducive to temperature rise. The tables are used to explain how physical parameters affect the Nusselt number and mass transfer. The increased interaction of the liquid with nanoparticles or dust particles is intended to improve the Nusselt number. This model contains features that have not been previously studied, which stimulates demand for this model among all walks of life now and in the future.

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