Study on Unsteady Motion of Gravity-driven Water Droplets in Soil Pores

摘要

Infiltration of liquid droplets into dry porous media has been widely modeled as liquid slug flow in capillaries.In this work, a math-ematical model was developed to model the gravity-driven slug motion in vertically oriented capillary tubes.Experiments on water slugs were conducted in partially wettable capillary tubes.Good agreements between the experimental and theoretical results demonstrated that the present model is capable of describing the unsteady-state dynamics of slugs fall in partially wettable capillaries.Then the developed model was applied to study the effects of contact angle and pore radium on slug dynamics.It showed that the slug falls down a longer distance at a larger average velocity for a smaller contact angle, and in a wide tube the slug had a larger average velocity than that in a narrow one.The model developed in this work could be employed to study how slugs propagate in porous media such as soils and help to explore the liquid droplets infiltration from a new point of view.

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