Proper Orthogonal Decomposition for the Study of Hydrodynamics in a Mixing Tank

摘要

The complex flow generated by a Rushton turbine is characterized both by a high-level of turbulence,and by a large-scale structure induced by the blade motion.These coherent structures are a counter-rotating vortex pair(Van'Riet and Smith,Van'Riet et al.,Escudie et al.).They are of critical importance in a mixing tanks,since they are linked with blending performance,gas cavities(in the case of an aereted tank)and turbulence production.It is assumed that the impact of these coherent trailing vorticies in flow-energy transfer is important,and it seems necessary to get a good evaluation of the part of the mean energy transfered to periodic motion,as well as from organized motion to turbulence.However,in an attempt to evaluate these transfers,several techniques have been used in the past.