ABSTRACT
Swirling flow occurs in a wide variety of situations; at the intakes to gas turbines operated near a ground surface; in pump sumps and intakes for hydro-electric schemes; in the common bath-tub and tea cup. Consequently, a wide variety of geometrical configurations and flow conditions have been used for both experimental and theoretical investigations. M. Y. M. Kamel has shown that the upward axial components probably occur where the flow through the boundary layer formed at the tank bottom exceeds the discharge capacity of the outlet, and so is forced upwards. Another form of correction has been suggested by J. Knauss. The method is only applicable for modelling air entraining vortices, and is not necessary when only investigating surface swirling. An initial swirl or circulation may or may not be superimposed. This arrangement produces relatively stable free-surface vortices and, together with the inherent axial symmetry, greatly simplifies both the experimental and theoretical treatment.
