The parameter g is the gravitational acceleration. Thus it is convenient
to replace P/V by the energy dissipation density ε = P/(V),
where is the fluid density, in order to describe both terms as
power inputs relative to the mass of the culture.
The only property of the medium that was considered as an
explicit variable, was the kinematic viscosity . There are several
possibilities showed that considering the viscosity
also allows tomake equation(3)dimensionally tight by formulating
it in a dimensionless way