Tsallis has proposed a generalization of Boltzmann-Gibbs thermostatistics b
y introducing a family of generalized nonextensive entropy functionals with
a single parameter q. These reduce to the extensive Boltzmann-Gibbs form f
or q = 1, but a remarkable number of statistical and thermodynamic properti
es have been shown to be q-invariant - that is, valid for any q. In this pa
per, we address the question of whether or not the value of q for a given v
iscous, incompressible fluid can be ascertained solely by measurement of th
e fluid's hydrodynamic properties. Mie find that the hydrodynamic equations
expressing conservation of mass and momentum are q-invariant., but the con
servation of energy is not. Moreover, we find that ratios of transport coef
ficients may also be q-dependent. These dependences may therefore be exploi
ted to measure q experimentally.