Fluidity aspects of Bose-Einstein condensed systems

We analyze some aspects of the fluidity of Bose-Einstein (BE) condensed systems. We show that a two-fluid picture of a condensed system holds true. The condensate is a quantum fluid component of the system. This component of the fluid satisfies the continuity equation and a generalized Bernoulli equation. Under certain conditions, the condensate component becomes a classical superfluid. We suggest that condensed systems might exhibit mechanochalorical and thermomechanical effects, in close analogy with superfluid helium-4. Quantized vortices are also expected to appear in a BE condensed system. We discuss the structure of quantized vortices.