Viscosity of Air at Different Temperatures and 101.325 kPa

In the particular case of fluids mixing, if linear dimensions such as the depth of liquid in the tank, the diameter of the tank, as well as the number, dimensions, and position of baffles are all in a definite geometrical ratio with the impeller diameter, then the power input to the agitator can be expressed as a function of the following variables  

Dimensional analysis indicates that Equation Al may be reexpressed to include powers in all the variables as follows  

If dimensions are given in terms of fundamental units, that is, mass M, length L, and time T, then by substituting such units of the variables. Equation A2 would transform into 

By equating fundamental units on both sides of Equation A3, and by algebraic means, common powers are grouped together to give 

Equation A5 is often referred to as the power equahon. The term on the left-hand side of the equation is known as the dimensionless power number, the first term after the constant k on the right-hand side of the equation is the dimensionless Reynolds number Re, while the last term of the equation is the dimensionless Froude number Fr. 

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