scholarly journals Effect of Liquid Droplet Deformation on the Displacement Due to Airstreams.

1998 ◽  
Vol 41 (4) ◽  
pp. 855-862
Author(s):  
Teruhiko YOSHIDA
Keyword(s):  
Liquid Droplet ◽  
Droplet Deformation

Comparison of Surface Tension Models in Smoothed Particles Hydrodynamics Method

2019 ◽  
Author(s):  
Lijing Yang ◽  
Milad Rakhsha ◽  
Dan Negrut
Keyword(s):  
Surface Tension ◽  
Liquid Droplet ◽  
Surface Force ◽  
Accurate Estimation ◽  
Droplet Deformation ◽  
Two Phase ◽  
Mesh Free ◽  
Interface Curvature ◽  
Particle Force ◽  
Smoothed Particles Hydrodynamics

Abstract We compare two surface tension models to solve two-phase fluid interaction problems in the context of the mesh-free Smoothed Particles Hydrodynamics (SPH) method. The Continuum Surface Force (CSF) model (later extended to Continuum Surface Stress, CSS), originally derived from grid-based numerical methods, requires an accurate estimation of the interface curvature to express the surface tension. Unlike CSF, the Inter-Particle Force (IPF) model is more robust in this regard as it draws on a molecular dynamics foundation by considering how the pairwise interaction forces between particles within a cutoff distance act in relation to producing the surface tension. Herein, we rely on second-order consistent gradient and Laplacian operators to improve the accuracy of SPH formulations as well as on a particle shifting technique to “disorder” particles from non-differentiable interface geometries. A 3D liquid droplet deformation test is used to compare CSF and IPF in terms of their pressure field and kinetic energy dissipation accuracy.

scholarly journals Droplet deformation by short laser-induced pressure pulses

2017 ◽  
Vol 828 ◽  
pp. 374-394 ◽  
Author(s):  
Sten A. Reijers ◽  
Jacco H. Snoeijer ◽  
Hanneke Gelderblom
Keyword(s):  
Pulse Duration ◽  
Pressure Pulse ◽  
Liquid Droplet ◽  
Density Fluctuations ◽  
Total Momentum ◽  
Shape Evolution ◽  
Analytic Model ◽  
Droplet Deformation ◽  
Droplet Shape ◽  
Free Falling

When a free-falling liquid droplet is hit by a laser it experiences a strong ablation-driven pressure pulse. Here we study the resulting droplet deformation in the regime where the ablation pressure duration is short, i.e. comparable to the time scale on which pressure waves travel through the droplet. To this end, an acoustic analytic model for the pressure, pressure impulse and velocity fields inside the droplet is developed in the limit of small density fluctuations. This model is used to examine how the droplet deformation depends on the pressure pulse duration while the total momentum to the droplet is kept constant. Within the limits of this analytic model, we demonstrate that when the total momentum transferred to the droplet is small the droplet shape evolution is indistinguishable from an incompressible droplet deformation. However, when the momentum transfer is increased the droplet response is strongly affected by the pulse duration. In this later regime, compressed flow regimes alter the droplet shape evolution considerably.

Gas-Assisted Droplet Impact on a Solid Surface

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Andres J. Diaz ◽  
Alfonso Ortega
Keyword(s):  
Solid Surface ◽  
High Speed ◽  
Liquid Droplet ◽  
High Speed Photography ◽  
Droplet Deformation ◽  
Droplet Spreading ◽  
Carrier Gas ◽  
Air Jet ◽  
Vof Model ◽  
Theoretical Predictions

An experimental, numerical, and theoretical investigation of the behavior of a gas-assisted liquid droplet impacting on a solid surface is presented with the aim of determining the effects of a carrier gas on the droplet deformation dynamics. Experimentally, droplets were generated within a circular air jet for gas Reynolds numbers Reg = 0–2547. High-speed photography was used to capture the droplet deformation process, whereas the numerical analysis was conducted using the volume of fluid (VOF) model. The numerical and theoretical predictions showed that the contribution of a carrier gas to the droplet spreading becomes significant only at high Weo and when the work done by pressure forces is greater than 10% of the kinetic energy. Theoretical predictions of the maximum spreading diameter agree reasonably well with the experimental and numerical observations.

Flow Induced Dynamics of a Pinned Droplet on the Surface of a Channel

2005 ◽  
Author(s):  
Amirreza Golpaygan ◽  
Nasser Ashgriz
Keyword(s):  
Surface Tension ◽  
Stokes Equations ◽  
Liquid Droplet ◽  
Equilibrium Shape ◽  
High Surface ◽  
Droplet Surface ◽  
Navier Stokes ◽  
Fluid Viscosity ◽  
Droplet Deformation ◽  
Newtonian Liquids

Dynamic behavior of a droplet adhering to the surface of a channel has been modeled under the influence of surrounding fluid. The numerical solution is based on solving Navier-Stokes equations for Newtonian liquids. The study includes the effect of interfacial forces with constant surface tension, also effect of adhesion between the wall and droplet accounted by implementing contact angle at the wall. The Volume-Of-Fluid method is used to numerically determine the deformation of free surface. Droplet deformation and final shapes have been predicted. A reduction in the surface tension allows the droplet to deform much easier. However, an increase in the fluid viscosity, although increases the shear force on the droplet, may not result in the deformation at high surface tension. It is shown that deformation of droplet significantly influences structure of channel flow. Effects of liquid droplet and channel fluid properties, namely density and viscosity, inlet velocity, surface tension and channel geometry on dynamics of the problem have been studied. Two different outcomes have been considered: the first one droplet with equilibrium shape and the other one when breakup of the droplet occurs. The border line between the disintegration region and equilibrium region is determined for different droplet surface tensions.

DIRECT INTERFACE TRACKING OF DROPLET DEFORMATION

2002 ◽  
Vol 12 (5-6) ◽  
pp. 721-736 ◽  
Author(s):  
David P. Schmidt ◽  
Meizhong Dai ◽  
Haoshu Wang ◽  
J. Blair Perot
Keyword(s):  
Interface Tracking ◽  
Droplet Deformation
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