A model of liquid outflow from single-outlet vessels

Abstract

This paper analyses the outflow of liquids from single-outlet vessels. In such vessels the liquid leaving the vessel through the outlet is replaced by another fluid, which enters the vessel through the same opening. A theoretical model is developed for the general case of gas—liquid systems. The model, based on a simplified description of the system, is derived from first principles, and contains one adjustable parameter. Irrespective of the numerical value of this parameter the model describes qualitatively the various phenomena observed experimentally, such as the linear variation between the large-scale gas void fraction in the vessel and the elapsed time. A correlation for the adjustable parameter is presented and its significance discussed. The model is in excellent agreement with the available experimental data on the variation of the large-scale gas void fraction in the vessel and the large-scale gas pressure in the vessel with elapsed time. The application of the model is also discussed.