Phase change modelling for non-isothermal flows: a mathematical, numerical and computational model for pure substances

The Computational Fluid Dynamic (CFD) is an important methodology to study the characteristics of flows in nature and in several engineering applications. Modelling non-isothermal flows may be usefull to predict the main flow dynamics which allows the improvement of efficiency in equipments and processes for industrial purpose. In addition, investigations using computational models may provide key information about the fundamental characteristics of flow, developing the theoretical groundwork of physical processes. In the last years, the topic of phase change has been intensively studied using CFD due to the computational and numerical advances reported in the literature. In the present work, phase change is studied using a mathematical, numerical and computational model developed in this thesis. The homemade code MFSim was used to run all the computational simulations in the cluster from the Fluid Mechanics laboratory (MFLab) from the Federal University of Uberlandia (UFU). The computational model was verified and validated against several cases from the literature. The model developed in the present thesis showed results with high accuracy and low differences compared to previous works in the literature. After the performance of several validation cases, some topics were deeply investigated. Finally, a complex case study of Direct contact condensation (DCC) was studied and the computational model provided accurate results compared to the literature. The present thesis reported the advances on modelling computationally the topic of phase change using the homemade code MFSim and several interesting conclusions were developed and some numerical issues were overcame. Boiling cases were validated against theoretical and analytical solution from the literature. The results show low deviations compared to the references. Finally, spurious currents magnitude were quantified for phase change problems and particular forces due to phase change were investigated. The results show null importance of these forces in the phase change model studied.