Numerical calculation of axisymmetric fluid-liquid interfaces by polar coordinate system and examples associated with U-Pu co-conversion technology

An exquisite shape of gas-liquid interface, that is a bubble/drop/liquid bridge, is the result of continuous pressure balance along vertical axis between the pressure due to difference of density and the pressure due to surface tension and curvature of interface. However, there have been surprisingly a little papers arguing the accurate shape, curvatures and volume. Regarding the research and development of U-Pu co-conversion technology, some phenomena were well understood by obtaining the accurate shape and/or volume. A numerical solving method by polar coordinate system with a switched-origin algorithm applicable to the shape that includes multiple tangential planes both in horizontal and in vertical was derived through such experiences, although static physical conditions and axisymmetrical property are assumed. The real interface shape is actualized or selected as a part of the calculated curve, which depends on physical conditions. A bubble at the tip of dip-tube used for density/level measurement, a bubble nucleates in the cylindrical shape of liquid heated by microwave and an estimated liquid bridge in the granule after co-conversion were described as actual examples. Interfaces between water and air under normal temperature and atmospheric pressure were described as numerical examples for systematic investigation. Contact angle, internal/external pressure difference, volume, surface energy and wavelength of periodically deforming shape are physical conditions actualizing the calculation. (author)