scholarly journals Statics and dynamics of liquid barrels in wedge geometries

2018 ◽  
Vol 842 ◽  
pp. 26-57 ◽  
Author(s):  
Élfego Ruiz-Gutiérrez ◽  
Ciro Semprebon ◽  
Glen McHale ◽  
Rodrigo Ledesma-Aguilar
Keyword(s):  
Surface Energy ◽  
Liquid Droplet ◽  
Symmetry Plane ◽  
Equilibrium Contact Angle ◽  
Opening Angle ◽  
Lagrangian Description ◽  
Quasi Equilibrium ◽  
Droplet Dynamics ◽  
Statics And Dynamics ◽  
Contact Line Friction

We present a theoretical study of the statics and dynamics of a partially wetting liquid droplet, of equilibrium contact angle $\unicode[STIX]{x1D703}_{e}$, confined in a solid wedge geometry of opening angle $\unicode[STIX]{x1D6FD}$. We focus on a mostly non-wetting regime, given by the condition $\unicode[STIX]{x1D703}_{e}-\unicode[STIX]{x1D6FD}>90^{\circ }$, where the droplet forms a liquid barrel – a closed shape of positive mean curvature. Using a quasi-equilibrium assumption for the shape of the liquid–gas interface, we compute the changes to the surface energy and pressure distribution of the liquid upon a translation along the symmetry plane of the wedge. Our model is in good agreement with numerical calculations of the surface energy minimisation of static droplets deformed by gravity. Beyond the statics, we put forward a Lagrangian description of the droplet dynamics. We focus on the overdamped limit, where the driving capillary force is balanced by the frictional forces arising from the bulk hydrodynamics, the corner flow near the contact lines and the contact-line friction. Our results provide a theoretical framework to describe the motion of partially wetting liquids in confinement, and can be used to gain further understanding on the relative importance of dissipative processes that span from microscopic to macroscopic length scales.

Water–substrate physico-chemistry in wetting dynamics

2015 ◽  
Vol 781 ◽  
pp. 695-711 ◽  
Author(s):  
Petter Johansson ◽  
Andreas Carlson ◽  
Berk Hess
Keyword(s):  
Friction Factor ◽  
Contact Line ◽  
Continuum Model ◽  
Large Scale ◽  
Phase Field Model ◽  
Equilibrium Contact Angle ◽  
Wetting Front ◽  
Droplet Dynamics ◽  
Dynamics Simulations ◽  
Contact Line Friction

We consider the wetting of water droplets on substrates with different chemical composition and molecular spacing, but with an identical equilibrium contact angle. A combined approach of large-scale molecular dynamics simulations and a continuum phase field model allows us to identify and quantify the influence of the microscopic physics at the contact line on the macroscopic droplet dynamics. We show that the substrate physico-chemistry, in particular hydrogen bonding, can significantly alter the flow. Since the material parameters are systematically derived from the atomistic simulations, our continuum model has only one adjustable parameter, which appears as a friction factor at the contact line. The continuum model approaches the atomistic wetting rate only when we adjust this contact line friction factor. However, the flow appears to be qualitatively different when comparing the atomistic and continuum models, highlighting that non-trivial continuum effects can come into play near the interface of the wetting front.

Ex-situ probing of PEFC liquid droplet dynamics in the presence of vibration

2017 ◽  
Vol 42 (17) ◽  
pp. 12551-12558 ◽  
Author(s):  
Justin T. Sellman ◽  
Anthony D. Santamaria
Keyword(s):  
Liquid Droplet ◽  
Ex Situ ◽  
Droplet Dynamics

Ring-Shaped Sessile Droplet

2011 ◽  
Author(s):  
Svyatoslav S. Chugunov ◽  
Douglas L. Schulz ◽  
Iskander S. Akhatov
Keyword(s):  
Contact Angle ◽  
Liquid Droplet ◽  
Liquid Structure ◽  
Solid Substrate ◽  
Contact Angles ◽  
Equilibrium Contact Angle ◽  
Sessile Droplet ◽  
System Equilibrium ◽  
Energy Consideration ◽  
External Forces

It is recognized that small liquid droplet placed on the solid substrate forms equilibrium contact angle that can be obtained from well-known Young’s law. Previously, deviations from Young’s law were demonstrated for the droplets exposed to external fields (gravity, electric, etc) and for the droplets on non-homogeneous substrates. This work reveals that the Young’s equilibrium contact angle can be altered by geometrical reasons only. We consider a ring-shaped droplet on a solid substrate as a test structure for our discussion. We use the global energy consideration for analysis of system equilibrium for the case of freely deposited liquid with no external forces applied. The theoretical analysis shows that steady ring-shaped liquid structure on a solid substrate does exist with contact angles on both contact lines to be different from the Young’s equilibrium contact angle.

Capillary spreading of a droplet in the partially wetting regime using a diffuse-interface model

2007 ◽  
Vol 572 ◽  
pp. 367-387 ◽  
Author(s):  
V. V. KHATAVKAR ◽  
P. D. ANDERSON ◽  
H. E. H. MEIJER
Keyword(s):  
Liquid Droplet ◽  
Spectral Element ◽  
Contact Angles ◽  
Diffuse Interface ◽  
Equilibrium Contact Angle ◽  
Interface Model ◽  
Governing Equations ◽  
Ambient Fluid ◽  
Diffuse Interface Model ◽  
Capillary Spreading

The spreading of a liquid droplet on a smooth solid surface in the partially wetting regime is studied using a diffuse-interface model based on the Cahn--Hilliard theory. The model is extended to include non-90$^{\circ}$ contact angles. The diffuse-interface model considers the ambient fluid displaced by the droplet while spreading as a liquid. The governing equations of the model for the axisymmetric case are solved numerically using a finite-spectral-element method. The viscosity of the ambient fluid is found to affect the time scale of spreading, but the general spreading behaviour remains unchanged. The wettability expressed in terms of the equilibrium contact angle is seen to influence the spreading kinetics from the early stages of spreading. The results show agreement with the experimental data reported in the literature.

scholarly journals Numerical modelling of liquid droplet dynamics in microgravity

2011 ◽  
Vol 327 ◽  
pp. 012027 ◽  
Author(s):  
S Easter ◽  
V Bojarevics ◽  
K Pericleous
Keyword(s):  
Numerical Modelling ◽  
Liquid Droplet ◽  
Droplet Dynamics

Oscillations of magnetically levitated aspherical droplets

1991 ◽  
Vol 224 ◽  
pp. 395-416 ◽  
Author(s):  
D. L. Cummings ◽  
D. A. Blackburn
Keyword(s):  
Surface Tension ◽  
Surface Energy ◽  
Liquid Droplet ◽  
Rotational Symmetry ◽  
Equilibrium Shape ◽  
Metal Droplet ◽  
Single Frequency ◽  
Restoring Force ◽  
Restoring Forces ◽  
Magnetically Levitated

In experiments to measure the surface energy of a magnetically levitated molten metal droplet by observation of its oscillation frequencies, Rayleigh's equation is usually used. This assumes that the equilibrium shape is a sphere, and the surface restoring force is due only to surface tension. This work investigates how the vibrations of a non-rotating liquid droplet are affected by the asphericity and additional restoring forces that the levitating field introduces. The calculations show that the expected single frequency of the fundamental mode is split into either three, when there is an axis of rotational symmetry, or five unequally spaced bands. Frequencies, on average, are higher than those of an unconstrained droplet; the surface tension appears to be increased over its normal value. This requires a small correction to be made in all analyses of surface energy. A frequency sum rule is derived from a simplified model of the magnetic field which allows the corresponding Rayleigh frequency to be evaluated from the observed frequencies of the fundamental and translational modes. A more detailed analysis shows a similar correction but one that is also sensitive to the position of the droplet in the field.

Liquid droplet movement on horizontal surface with gradient surface energy

2006 ◽  
Vol 49 (6) ◽  
pp. 733-741 ◽  
Author(s):  
Qiang Liao ◽  
Hong Wang ◽  
Xun Zhu ◽  
Mingwei Li
Keyword(s):  
Surface Energy ◽  
Liquid Droplet ◽  
Horizontal Surface ◽  
Droplet Movement ◽  
Gradient Surface

3D Modeling for Wet-Compression in a Single Stage Compressor Including Liquid Particle Erosion Analysis

2010 ◽  
Author(s):  
Jobaidur R. Khan ◽  
Ting Wang
Keyword(s):  
Liquid Droplet ◽  
Computational Simulation ◽  
Turbulence Models ◽  
Continuous Phase ◽  
Droplet Breakup ◽  
Local Thermal Equilibrium ◽  
Local Pressure ◽  
Droplet Dynamics ◽  
Erosion Model ◽  
Wet Compression

Gas turbine inlet fog / overspray cooling is considered as a simple and effective method to increase power output. To help understand the water mist transport in the compressor flow passage, this study conducts a 3-D computational simulation of wet compression in a single rotor-stator compressor stage using the commercial code, Fluent. A sliding mesh scheme is used to simulate the stator-rotor interaction in a rotating frame. Eulerian-Lagrangian method is used to calculate the continuous phase and track the discrete (droplet) phase respectively. Models to simulate droplet breakup and coalescence are incorporated to take into consideration the effect of local acceleration and deceleration on water droplet dynamics. Analysis on droplet history (trajectory and size) with stochastic tracking is employed to interpret the mechanism of droplet dynamics under the influence of local turbulence, acceleration, diffusion, and body forces. An liquid-droplet erosion model is included. The sensitivity of turbulence models on the results is conducted by employing 6 different turbulence models and 4 different time constants. The result shows that the local thermal equilibrium is not always achieved due to short residence time and high value of latent heat of water. Local pressure gradients in both the rotor and stator flow passages drive up the droplet slip velocity during compression. The erosion model predicts that the most eroded area occurs in leading edge and one spot of trailing edge of the rotor suction side.

Liquid droplet dynamics and complex morphologies in vapor–liquid–solid nanowire growth

2011 ◽  
Vol 26 (17) ◽  
pp. 2186-2198 ◽  
Author(s):  
E.J. Schwalbach ◽  
S.H. Davis ◽  
P.W. Voorhees ◽  
D. Wheeler ◽  
J.A. Warren
Keyword(s):  
Liquid Droplet ◽  
Nanowire Growth ◽  
Vapor Liquid Solid ◽  
Droplet Dynamics ◽  
Image Position ◽  
Vapor Liquid

Abstract

Sign in / Sign up

Export Citation Format

Share Document