There is no simple rule of thumb for power estimation in either turbulent or
laminar mixing. Power depends on impeller type, number of blades, blade
width but especially impeller diameter and rotational speed. Power is
proportional to impeller diameter to the fifth power and rotational speed
cubed for turbulent conditions. Power is proportional to impeller diameter
cubed and rotational speed squared for laminar conditions.

Turbulent and laminar conditions also depend on impeller diameter and
rotational speed, but as a rough estimate turbulent conditions probably
exist for viscosities less than 100 cp and laminar conditions for
viscosities greater than 1,000,000 cp. Between turbulent and laminar
conditions is a transition range.