Analysis of validation of the semi-implicit FEM algorithm for natural convection and freezing of water

Authors' experimental findings are used to determine the scope of validation of the two-dimensional FEM model proposed in calculation of natural convection and solidification of pure water in a cube-shaped enclosure. In the empirical investigations, modern full field experimental techniques based on the digital image analysis are applied, where Digital Particle Image Velocimetry and Thermometry, with computational analysis of color and displacement of liquid crystal tracers, provide quantitative data of two-dimensional temperature and velocity fields. The empirical results thus obtained are further compared with the calculations performed by the use of the semi-implicit operator splitting technique tied with the enthalpy porosity method on a fixed finite element grid. Scopes of both the agreement and the incongruity of the experimental and numerical results are analyzed and potential reasons of visible inconsistency in the local structure of the free convection flow are discussed. Finally, some general remarks and conclusions are given concerning the verification procedure of accuracy of numerical simulation for complex conjugate heat transfer and solidification problems, when experimental benchmarks are used.