A Variable Time Step Time Filter Algorithm for the Geothermal System

This paper proposes a variable time step, second-order time filter algorithm for the closed-loop geothermal system for the first time. The algorithm is easy to implement in programming, which greatly improves calculation efficiency, while improving the accuracy of convergence. Theoretically, we mainly analyze the stability and the convergence of the algorithm in the case of variable time steps. Finally, numerical experiments confirm the theoretical results and show that the algorithm can simulate geothermal system well.