Non-Axisymmetric Effects on Long Liquid Bridges

The stability of long liquid bridges under non-axisymmetric disturbances like a microgravitational force acting perpendicular to the liquid bridge axis or a non-coaxiality of the disks is analyzed through an asymptotic method based on bifurcation techniques. Results obtained indicate that such non-axisymmetric effects are of higher order than those produced by axisymmetric perturbations

Non-steady Phenomena in the Vibration of Viscous Cylindrical Long Liquid Bridges

This paper deals with the dynamic response of long cylindrical viscous liquid bridges subjected to an oscillatory microgravity field whose frequency varies linearly with time. The problem has been solved by using a one-dimensional model for the dynamics, derived from Cosserat theory for continuum, in which the axial velocity is considered to be constant over each cross-section of the liquid column. The dynamic response of the liquid bridge has been obtained by applying the Laplace transform to the problem formulation. The results obtained show that a variable -frequency excitation could give rise to erroneous measurements of the resonance frequencies of viscous liquid bridges

Dynamics of nearly unstable axisymmetric liquid bridges

The dynamics of a noncylindrical, axisymmetric, marginally unstable liquid bridge between two equal disks is analyzed in the inviscid limit. The resulting model allows for the weakly nonlinear description of both the (first stage of) breakage for unstable configurations and the (slow) dynamics for stable configurations. The analysis is made for both slender and short liquid brides. In the former range, the dynamics breaks reflection symmetry on the midplane between the supporting disks and can be described by a standard Duffing equation, while for short bridges reflection symmetry is preserved and the equation is still Duffing-like but exhibiting a quadratic nonlinearity. The asymptotic results compare well with existing experiments

Stability and bifurcation Problems for Equilibrium States of a Liquid Bridge

The results of an investigation on the stability of a doubly connected axisymmetric equilibrium free surface pinned to the edges of two coaxial disks are presented. The general boundary of the region where the interface is stable is constructed in the plane of the parameters determining the slenderness of a liquid bridge and its relative volume. Surface forces and arbitrary (not only axisymmetric) perturbations are taken into account. The general boundary of the stability region was calculated completely in the past only for a weightless fixed-contactline liquid bridge between equal disks. The influence of axially directed gravity, isorotation and disks inequality on the evolution of this boundary has been analyzed successively. As a result, the families of the stability boundaries have been obtained for fixed-contact-line liquid bridges between equal disks in a wide range of Bond numbers, for isorotating weightless bridges between equal disks, in a wide range of Weber numbers and for weightless fixed-contact-line liquid bridges when the disk radii ratio is varied. Basing on the solution of the bifurcation problem for the critical equilibrium states, the conclusion on the results of stability losing has been made for starting system of fixed-contact line weightless bridge between equal-disks. The stability of the melt during crystal growth using the floating zone technique can be considered as a special case of the presented results. Finally as an example, for a crystal growth system using the Stepanov's method the effect of free surface unconnectivity on the stability has been investigated under zero gravity conditions

Experimental analysis of the vibration of a liquid bridge under microgravity conditions.

The experimental results obtained of the experiment \LICOR" made on board the Spacelab D-2 Mission are analyzed. The conguration consisted of a liquid bridge where one of the supporting disks was vibrated. The recorded images are analyzed and the measured behaviour compared with the results of one dimensional models. The results of two pressure sensors located in each of the supporting disks are also analyzed

Experimental analysis of the breakage of a liquid bridge under microgravity conditions.

The experimental results obtained of the experiment \STACO" made on board the Spacelab D-2 Mission are analyzed. The conguration consisted of a liquid bridge between two solid supporting disks. An expected breakage occurred during the experiment. The recorded images are analyzed and the measured behaviour compared with the results of three dimensional model

A Theoretical Approach to Impulsive Motion of Viscous Liquid Bridges

This paper deals with the dynamics of isothermal, axisymmetric, viscous liquid columns held by capillary forces between two circular, concentric, solid disks. The transient response of the bridge to an excitation consisting of a small change in the value of the acceleration acting along its axis has been solved by using a linearised one-dimensional Cosserat model, which includes viscosity effects. The main hypothesis of this model is that the axial velocity is considered constant in each section of the liquid bridge. The analysis has been performed by using the Laplace transform

Stability of Liquid Bridges between Unequal Disks under Zero-Gravity Conditions

The stability, of axisymmetric equilibrium shapes of a liquid bridge between two coaxial disks of different radii under zero-gravity conditions is investigated. The stability regions have been evaluated for different values of the ratio of the disk radii in terms of the dimensionless parameters which characterize the length and the volume of the bridge. It has been found that disk radii unequality radically changes the upper boundary of the stability region. The analysis of the shape of marginally stable equilibrium surfaces has been carried out. Relationships between the critical values of the parameters have been deduced for some particular cases, which are of special interest for the materials purification processes and growing of single crystals by the floating zone method: for typical values of the growing angle for semiconductor materials and for liquid volumes close to that of the cylinder having a radius equal to the mean radius of the disk

Response of a liquid bridge to an acceleration varying sinusoidally with time

The response of a long cylindrical liquid column subjected to an axial microgravity field has been experimentally studied on a TEXUS sounding rocket flight to check with theoretical predictions. The expected response of the liquid bridge was a quasi-static amphora-type deformation of the cylindrical shape. However, the experimental results showed a more complex behaviour. Nevertheless it has been possible to find out the reasons of this discrepancy except for a mysterious 0.5% uncertainty in the stimuli

Dinámica de Puentes Líquidos

En estas paginas se presentan los resultados obtenidos en el experimento LICOR (Liquid Column Resonances) realizado a bordo del Spacelab durante la mision SL-D2 en abril de 1993. Aunque el analisis del experimento (la respuesta a oscilaciones forzadas de un puente liquido) aun no ha finalizado, los resultados preliminares indican que los resultados expenmentales estan en concordancia con las predicciones teoricas, tanto cualitativa como cuantitativamente