  We introduce a partitioned coupling approach for iterative coupling of flow
processes in deformable fractures embedded in a poro-elastic medium that is
enhanced by interface quasi-Newton (IQN) methods. In this scope, a unique
computational decomposition into a fracture flow and a poro-elastic domain is
developed, where communication and numerical coupling of the individual solvers
are realized by consulting the open-source library preCICE. The underlying
physical problem is introduced by a brief derivation of the governing equations
and interface conditions of fracture flow and poro-elastic domain followed by a
detailed discussion of the partitioned coupling scheme. We evaluate the
proposed implementation and undertake a convergence study to compare a
classical interface quasi-Newton inverse least-squares (IQN-ILS) with the more
advanced interface quasi-Newton inverse multi-vector Jacobian (IQN-IMVJ)
method. These coupling approaches are verified for an academic test case before
the generality of the proposed strategy is demonstrated by simulations of two
complex fracture networks. In contrast to the development of specific solvers,
we promote the simplicity and computational efficiency of the proposed
partitioned coupling approach using preCICE and FEniCS for parallel
computations of hydro-mechanical processes in complex, three-dimensional
fracture networks.
