Development of Numerical Codes by Direct Boundary Integral Method for Three-dimensional Non-steady Heat Conduction.

Final purpose of this study is to develop a subsystem which constructs three-dimensional numerical system in order to contribute to predictive calculation of output and life of Hot Dry Rock geothermal energy generation. The authors have developed the two kind of the systems for 3D non-steady heat conduction by the direct boundary element methods, the TIME INTEGRAL method and the STEP WISE method. They have carried out numerical calculations by using the system developed and have shown applicability of the system, especially in aiming to high precision and high speed computation. In this report, the outline of the unique procedure of the numerical system developed by the authors is described first, the calculated results on heat conduction in a sphere solid is compared with the corresponding strict solution and accuracy of numerical solution is demonstrated next. Finally, the strict solution of heat conduction in infinite medium around a spherical cavity is originally presented and the numerical solution of it is compared with the strict solution.