  Hydrodynamic model simulations of Au-Au collisions at RHIC have indicated
recently, that with improved simulations in the coming years, it may be
feasible to quantify the viscosity of the matter produced in heavy ion
collisions. To this end, a consistent fluid dynamic description of viscous
effects is clearly needed. In this note, we observe that a recently used,
approximate form of the 2nd order Israel-Stewart viscous hydrodynamic equations
of motion cannot account consistently for the transverse flow fields, which are
expected to develop in heavy ion collisions. We identify the appropriate
equations of motion.
