Exploration on the reverse calculation method of groundwater velocity by means of the moving line heat source

The research on the influence that groundwater exerts on borehole ground heat exchanger has been made progress. However, the investigation on how to obtain the groundwater velocity is a little. According to the line heat source model with groundwater flow, a new methodology is explored to obtain the value and direction of groundwater velocity while it flows through borehole. Some points are distributed around borehole and they have the same distance to the center line of borehole, and the temperature responses of these points are significant parameters which lay firm foundation for reverse-reasoning. The reverse-reasoning calculation can be conducted by establishing objective function. The comparisons of temperature responses between theoretical results and the simulative recorded data are made. The impact degree of groundwater flow can be displayed and then the velocity is estimated. Differences among points' temperature responses are made full use of to respectively indicate the direction and value ranges of velocity. The relativity between the points' location and the velocity intensity is investigated and then some cases are chosen as the trials to verify the rationality of reverse calculation method. To a large extent, the research work of this paper provides theoretical guidance or computing mode for getting velocity of groundwater. The methodology can be employed for obtaining the velocity in actual engineering projects or other cases.