Ergun-type equations don’t enable to account for near-wall effects due to higher local void fraction close to the walls, and which may affect overall pressure losses of the bed. In order to account for near-wall effects, Rose and Rizk (1949), constructed a chart (Fig. 22) to determine...
Studying this equation, we see that the largest eddies’ size depends on the coordinate 𝑥2x2 which is very meaningful as, for example, the active eddies at a location 𝑥2x2 above a wall, which is positioned at 𝑥2=𝑥2𝑚𝑖𝑛x2=x2min (by the no-slip boundary condition the...