The interface capturing method of incompressible two-phase flow (including single-phase flow) with surface tension without mass transfer is presented. The interface between the two phases is tracked with the level set function, which can be advected with a background flow field propagating the interface exactly as the zero level set. It maintains the property of a distance function indicating the shortest distance to the interface. The level set and Navier-Stokes equations are solved on the fixed Cartesian staggered grid by a finite difference method. Moreover, a high order numerical scheme is applied for these governing equations to reduce numerical instability and excessive mass loss. In this paper, it is emphasized to derive the numerical implementation of these equations from the standpoint of practicality. The basic software is programmed in Java and some numerical examples are analyzed.
It is important to understand the geothermal reservoir behavior in order to produce geothermal fluid for a long time. Micro-gravity measurement is one of the suitable methods for geothermal reservoir monitoring. In the Takigami geothermal field, we have conducted repeat micro-gravity measurements using Scintrex CG-3 and CG-3M relative gravimeters since before 1996, when the Takigami geothermal power plant started power generation. We estimated the gravity change caused by shallow part fluid flow by using a computer code which calculates gravity change caused by precipitation. We divided the Takigami geothermal area into 3 areas and 5 stages from the pattern of the gravity change during 1996 and 2008. Based on these stages, we made a conceptual reservoir model of the Takigami geothermal field.