  Landau was the first to advance hydrodynamic concepts such as density and
velocity to describe the superfluidity of liquid He$^4$. Due to the recent
spectacular success of experiments demonstrating Bose Einstein condensation in
dilute Bose atomic gases, interest has been revitalized in the theoretical
description of Bose Einstein condensates. Many of the properties of these gases
were obtained by using the Gross-Pitaevskii equation (GPE) to derive the
hydrodynamic equations for the gases. However, it is interesting to apply the
hydrodynamic equations obtained by Yee for bosons. Many of the properties
obtained for the dilute Bose gases are also consequences of Yee's hydrodynamic
equations, which derive from a formalism distinct from that of the GPE.
