A fast and highly efficient numerical computational method has important practical significance for development and application of the technology in groundwater source heat pumps. Normally the boundary of an aquifer has an irregularshape. Compared with unstructured grids, adopting structured grids can effectively decrease the complexity in discretization of the mathematical equations and is very beneficial for developing an adaptive mesh refinement (AMR) algorithm to simulate the seepage flow field of groundwater source heat pump system. To develop a computational method based on the structured grids, a simple pretreatment method was proposed to deal with the grid cells on the aquifer boundary. In the method, the effective permeability on the interfaces between grid cells rather than those of the grid cells was involved in computations, further an algorithm for calculating the effective permeability on the six faces of a grid cell was proposed. The threedimensional computational examples show that even more coarse cells are adopted a more accurate result can be reached for a domain with irregular boundary. In the AMR algorithm the cell sizes depend on the temperature gradient, i.e. the smaller cell size the lower the gradient; as a result of this, the time consuming for simulating the underground seepage flow in a groundwater source heat pump system is reduced considerably but the accuracy remains the same.
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