**6. Summary**

The fiber orientation phenomenon can be simulated either on a macro- or micro-scale by using current numerical techniques and state-of-the-art modelling approaches. Macroscopic fiber orientation models are computationally efficient and are the preferred solution for estimating fiber orientation in large industrial applications. The limitation of those models is their phenomenological nature and the dependency on a set of fitting parameters. The challenge is typically the correct choice of parameters for a specific material. On the other hand, microscopic fiber models have a larger physical basis, but since fibers are explicitly discretized they are not suitable for large-scale simulations, because they are computational expensive. A combination of the models from the two scales can relieve the individual shortcomings and provides an interesting numerical solution for the virtual engineering design of fiber-reinforced polymer parts. One possibility is the prediction of optimal macroscopic parameters by a microscopic simulation, or the derivation of a macroscopic data-driven model using microscopic simulation results as input data.

**Author Contributions:** Conceptualization, S.K.K.; Writing—Original Draft Preparation, S.K.K.; Writing—Review and Editing, T.O., A.K. and C.C.; Visualization, S.K.K.; Supervision, T.O., A.K. and C.C. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
