  Flow in fractured porous media occurs in the earth's subsurface, in
biological tissues, and in man-made materials. Fractures have a dominating
influence on flow processes, and the last decade has seen an extensive
development of models and numerical methods that explicitly account for their
presence. To support these developments, we present a portfolio of four
benchmark cases for single-phase flow in three-dimensional fractured porous
media. The cases are specifically designed to test the methods' capabilities in
handling various complexities common to the geometrical structures of fracture
networks. Based on an open call for participation, results obtained with 17
numerical methods were collected. This paper presents the underlying
mathematical model, an overview of the features of the participating numerical
methods, and their performance in solving the benchmark cases.
