“…For example, the author Wang [4] investigated the influence of impeller width on an impeller with a diameter of 195 mm, but also tested the influence of impeller width on an impeller with a diameter of 180 mm. To distinguish between these two primary investigations of the same article for the same assessed parameter, we used the notation Wang [4] Several studies were not integrated into this review because of their internal scaling (e.g., [20][21][22]), missing data (e.g., [15]), ambiguous representation of the data (e.g., parts of [2]), non-experimental nature and/or missing validation of the simulations (e.g., [23][24][25][26][27][28][29]). Some primary studies varied more than one parameter at a time when reporting the characteristics ( [1,2,4,9,11,17] and [8] (similar in [30])).…”