“…However, their solution to problems with complex geometries and boundary conditions required the development of efficient numerical solution techniques and the ability to implement these techniques on computers. The development of both numerical techniques and digital machines with increased computational power allowed for the wide application of CFD methods to many areas of fluid dynamics during the last few decades, including water and wastewater engineering [20,17,33,24,14,22,35,41,40,12,49,42,16,38,26,30] . Recently, CFD methods were also applied to study flows inside anaerobic digesters.…”