ABSTRACT
Measurement of variables directly related to vortices, such as the depth of the air core, is difficult as the vortex itself is usually not steady even for the presumed steady flow field. H. O. Anwar has conducted experiments showing that a vortex can be dissipated with a roughened bottom for flow conditions where a strong vortex would otherwise exist. A basic choice in classifying vortices is between visual techniques and the measurement of some quantity directly or indirectly dependent on the strength of vortices. In many applications, submerged may be even more detrimental than free surface vortices, particularly when occurring in 'wet pit' pump intakes. The basic idea is that stronger vortices are needed to ingest more buoyant material, the material varying from neutral density to floating trash, to air. Measurement of the tangential velocity at a known distance from the vortex center is sufficient to establish a fundamental vortex feature, the circulation.
