Stokes Law Formula- Usefulness and Limitations

Question 1

Limitations

Answer 1

The Stokes Law Formula holds only for spherical particles and under conditions where the Reynolds number is small less than 0.5.

Its use is limited to spherical like particles like sand and grit of a very small diameter. The velocity of larger particles wouldn’t be accurate using the equation, neither would the flocs of biomass which can build up any shape.

Question 2

Usefulness

Answer 2

The equation can give the first estimation of required settlement periods, minimal particle size or settlement efficiency.

For more accurate info actual particle size and sinking velocity should be measured = filamentous microbes.