To keep biogas production competitive against alternatives in the energy sector, operating costs of biogas plants must be reduced. Up to 50% of the energy consumption in biogas plants is contributed by mixing of biomass slurry. Thus, optimization of the mixing system is a promising approach to increase the overall efficiency of biogas plants. Investigations to find the optimal conditions of mixing are challenging in full-scale biogas digesters. Two main strategies to study biomass mixing in laboratories are to build a scale-down digester using an artificial substrate to mimic biomass, and to develop a computational fluid dynamics (CFD) model to simulate the mixing process. In this paper, a combined approach is carried out: a CFD model is presented and verified experimentally.