Phase field modeling of liquid jets in low gravity

Abstract

An axisymmetric phase field model is developed and used to model surface tension forces on liquid jets in microgravity. The previous work in this area is reviewed and a baseline drop tower experiment selected for model comparison. The model is solved numerically with a compact fourth order stencil on an equally spaced axisymmetric grid. After grid convergence studies, a grid is selected and all drop tower tests modeled. Agreement was assessed by comparing predicted and measured free surface rise. Trend wise agreement is good but agreement in magnitude is only fair. Suspected sources of disagreement are the simple turbulence model and the existence of slosh baffles in the experiment that were not included in the model. Parametric investigation was conducted to study the influence of key parameters on the geysers formed by jets in microgravity. Investigation of the contact angle showed the expected trend of increasing contact angle increasing geyser height. Investigation of the tank radius showed some interesting effects and demonstrated the zone of free surface deformation is quite large. Variation of the surface tension with a laminar jet showed clearly the evolution of free surface shape with Weber number. A breakthrough Weber number of 1 was predicted by the variation of the surface tension model which is close to the experimentally measured Weber number of 1.5 found in prior experimental work.