A Numerical Analysis on Flow in Hydrothermal Systems

Abstract

In this paper it is examined how writing specialized codes within the OpenFOAM software framework is applicable to problems involving hydrothermal systems. This is done with two case studies. In the first one, the continuity of mildly compressible flow is stabilized using Fréchet derivatives, enabling the use of very large time steps or treating it as steady state. The second one involves the phase change of water, due to sudden drop in pressure at the top of a water column. The physical properties are determined from the IAPWS-IF97 thermodynamic formulation, which is directly compiled into OpenFOAM. It is also demonstrated how the software framework is able to handle the numerical instabilities that are caused by the discontinuities in physical properties in the phase change region. Both cases demonstrate how the modular nature of the OpenFOAM can be utilized to solve specialized problems involving hydrothermal systems and are validated by analytical solutions.