Dynamics of an axisymmetric liquid bridge close to the minimum-volume stability limit

Abstract

We analyze both theoretically and experimentally the dynamical behavior of an isothermal axisymmetric liquid bridge close to the minimum-volume stability limit. First, the nature of this stability limit is investigated experimentally by determining the liquid bridge response to a mass force pulse for volumes just above that limit. In our experiments, the liquid bridge breakup takes place only when the critical volume is surpassed and is never triggered by the mass force pulse. Second, the growth of the small-amplitude perturbation mode initiating the liquid bridge breakage is measured experimentally and calculated from the linearized Navier-Stokes equations. The results of the linear stability analysis allow one to explain why liquid bridges with volumes just above the stability limit are so robust. Finally, the nonlinear process leading to the liquid bridge breakup is described from both experimental data and the solution of the full Navier-Stokes equations. Special attention is paid to the free-surface pinchoff. The results show that the flow becomes universal (independent of both the initial and boundary conditions) sufficiently close to that singularity and suggest that the transition from the inviscid to the viscous regime is about to take place in the final stage of both the experiments and numerical simulations.

Measurement of surface and interfacial tension using pendant drop tensiometry

“…The concept of measuring contact angle and interfacial tension simultaneously is appealing for many applications, particularly where fluids are being selected for (micro) fluidic handling applications. Recent work has extended the pendant drop technique to enable measurement of contact angle, by the introduction of a secondary solid surface in the form of a flat substrate [23][24][25] or particle [26]. In certain circumstances, this has the added benefit of applying a secondary force that allows measurement of interfacial tension at low or even zero Bond numbers [26].…”

“…More recently, the pendant drop method has been further developed to include a wider variety of drop configurations, from capillary bridges between two parallel plates [23][24][25] to compound pendant drops [26] formed when a spherical particle is attached to a pendant drop. These configurations have provided a significant extension to pendant drop tensiometry as they enable the method to accurately measure interfacial tensions for Bond numbers as low as zero [26].…”

Measurement of relaxation times in extensional flow of weakly viscoelastic polymer solutions

“…The filament thinning is triggered a capillary instability (Anna and McKinley 2001) and the subsequent evolution of the filament thread for Newtonian fluids is the result of the competition between the driving surface tension, viscosity, and inertial effects, with the filament diameter decreasing linearly with time in the last stage of the breakup process (Entov and Hinch 1997;Vega et al 2014).…”

Effects of surface-active impurities on the liquid bridge dynamics

“…In fact, ω → 0 in the minimum volume stability limit (Vega et al 2014). The differences between the values measured in the three environments for a given T must be attributed to the different liquid bridge volumes and Bond numbers (surface tensions) at that instant.…”

“…Steps 2-7 were repeated until the liquid bridge broke up at the minimum volume stability limit (Slobozhanin and Perales 1993;Vega et al 2014). In those cases where the evaporation rate was sufficiently high, the liquid bridge volume decreased spontaneously through the liquid evaporation.…”