A numerical study on the thermal capillary-buoyancy convection of a binary mixture driven by rotation and surface-tension gradient in a shallow annular pool

2021 ◽  
Vol 171 ◽  
pp. 121035
Author(s):  
Cheng-Zhi Zhu ◽  
Lan Peng ◽  
Jia-Jia Yu ◽  
You-Rong Li
Keyword(s):  
Surface Tension ◽  
Binary Mixture ◽  
Numerical Study ◽  
Surface Tension Gradient ◽  
Annular Pool ◽  
Buoyancy Convection

NUMERICAL STUDY OF PATTERNS AND THEIR EVOLUTION IN FINITE GEOMETRIES

1996 ◽  
Vol 06 (10) ◽  
pp. 1883-1890 ◽  
Author(s):  
J. PONTES ◽  
C.I. CHRISTOV ◽  
M.G. VELARDE
Keyword(s):  
Surface Tension ◽  
Numerical Study ◽  
Surface Tension Gradient ◽  
Thermal Gradients ◽  
Finite Geometries ◽  
Relative Value ◽  
Finite Layer ◽  
Spatio Temporal ◽  
Buoyancy Driven Convection ◽  
Conductive State

Pattern formation in a finite layer of fluid induced either by buoyancy or by a surface-tension gradient is considered. The fluid is confined between poor conducting horizontal boundaries, leading to patterns with a characteristic horizontal scale much larger than the fluid depth. The evolution of the system is studied by numerical integration of the (1+2)D equation introduced by Knobloch [1990]: [Formula: see text] Here µ is the scaled bifurcation parameter, κ=1, and a represents the effects of a heat transfer finite Biot number. The coefficients β, δ and γ do not vanish when the boundary conditions at top and bottom are not identical (β≠0, δ≠0) or when non-Boussinesq effects are taken into account (γ≠0). When the conductive state becomes unstable due to surface-tension inhomogeneities, it is shown that the system evolves towards a stationary pattern of hexagons with up or down flow depending on the relative value of the coefficients β and δ. In the case of buoyancy-driven convection (β=δ≠0), the system displays a tesselation of steady squares. Knobloch’s equation also describes time-dependent patterns at high thermal gradients, including spatio-temporal chaos, due to the non-variational character of the equation.

scholarly journals Study on the Instability of Two-Phase Flow in the Heat-Absorbing Tube of Trough Solar Collector

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Ying Zhang ◽  
Peiyao Liu ◽  
Peisheng Li ◽  
Yue Chen ◽  
Yanni Pan
Keyword(s):  
Surface Tension ◽  
Temperature Gradient ◽  
Velocity Gradient ◽  
Marangoni Effect ◽  
Surface Tension Gradient ◽  
Promoting Effect ◽  
Two Phase ◽  
Buoyancy Convection ◽  
Interface Wave ◽  
Rayleigh Benard

The Marangoni effect and Rayleigh-Benard effect in the two-phase region of solar trough heat-absorbing tube are simulated by FTM (front tracking method). Considering the Marangoni effect alone, although surface tension gradient and surface tension affect the interface wave, the two effects have different characteristics. The surface tension gradient caused by the temperature gradient is one of the factors that swing the interface. The amplitude attenuation of the interface wave decreases with the increase of the Marangoni number (Ma). In general, the surface tension gradient enhances the convection opposite to the temperature gradient. Under the gravity field, the Rayleigh-Benard effect influences the development of the vortex structure in the flow field, which in turn affects the velocity gradient near the interface to influence the evolution of the interface fluctuation. In a small Rayleigh number (Ra), the buoyancy convection reduces the velocity gradient, thus suppressing the evolution of the interfacial wave. In the range of Ra < 4.0E4, the larger the Ra, the stronger the inhibitory effect. However, when the Ra number is large (Ra > 4.0E4), the situation is just the opposite. The larger the Ra is, the stronger the promoting effect is.

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

Investigation of Three-Dimensional Flow in Microchannels With Patterned Surfaces

2007 ◽  
Author(s):  
Auro Ashish Saha ◽  
Sushanta K. Mitra
Keyword(s):  
Surface Tension ◽  
Flow Instability ◽  
Numerical Study ◽  
Three Dimensional ◽  
Surface Characteristics ◽  
Bottom Wall ◽  
Surface Tension Effect ◽  
Hydrophobic Region ◽  
Side Walls ◽  
Dimensional Simulation

A three-dimensional numerical simulation of flow in patterned microchannel with alternate layers of hydrophilic and hydrophobic surfaces at the bottom wall is studied here. Surface characteristics of the microchannel are accounted by specifying the contact angle and the surface tension of the fluid. Meniscus profiles with varying amplitude and shapes are obtained under the different specified surface conditions. Flow instability increases as the fluid at the bottom wall traverses alternately from hydrophilic region to hydrophobic region. To understand the surface tension effect of the side walls, a two-dimensional numerical study has also been carried out for the microchannel and the results are compared with three-dimensional simulation. The surface tension effect of the side walls enhances the capillary effect for three-dimensional case.

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.

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