Thermal performance of a ground heat exchanger in a cold climate: a CFD study Hossein Fatahian, Hessam Taherian, Hesamoddin Salarian and Esmaeel Fatahian Eur. Phys. J. Plus, 136 3 (2021) 265 Published online: 01 March 2021 DOI: 10.1140/epjp/s13360-021-01265-7