  This paper proposes a parallel numerical algorithm to simulate the flow and
the transport in a discrete fracture network taking into account the mass
exchanges with the surrounding matrix. The discretization of the Darcy fluxes
is based on the Vertex Approximate Gradient finite volume scheme adapted to
polyhedral meshes and to heterogeneous anisotropic media, and the transport
equation is discretized by a first order upwind scheme combined with an Euler
explicit integration in time. The parallelization is based on the SPMD (Single
Program, Multiple Data) paradigm and relies on a distribution of the mesh on
the processes with one layer of ghost cells in order to allow for a local
assembly of the discrete systems. The linear system for the Darcy flow is
solved using different linear solvers and preconditioners implemented in the
PETSc and Trilinos libraries. The convergence of the scheme is validated on two
original analytical solutions with one and four intersecting fractures. Then,
the parallel efficiency of the algorithm is assessed on up to 512 processes
with different types of meshes, different matrix fracture permeability ratios,
and different levels of complexity of the fracture network.
