
Dimensional Analysis and Scaling




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9.1 The philospher's approach to dimensional analysis (02:38)
Nature does not know about manmade measurements, such as metres, seconds, and kilograms. For a natural description of a flow, we need to remove these manmade measurements. This is the basis of the Buckingham Pi law.




9.2 The mathematician's approach to dimensional analysis (04:27)
A mathematician would write the dimensional NavierStokes equation in dimensionless form, by defining the smallest possible number of reference scales at the start of the problem and then writing every term in the equation in terms of these reference scales. Nondimensional numbers naturally drop out of this process.




9.3 The engineer's approach to dimensional analysis (02:33)
The engineer's approach to dimensional analysis is firmly rooted in the philosopher's approach and the mathematician's approach. This clip shows a systematic way to determine the dimensionless numbers in a problem.




9.4 to 9.6 Examples of dimensional analysis (12:10)
This clip shows examples of dimensional analysis applied to the total pressure drop across an orifice plate, the drag on an aeroplane, and the drag on a ship.




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