Abstract
Although the cardinal attribute of turbulence is the velocity fluctuations, these fluctuations have been ignored in theories of the frictional drag of turbulent flows. Our goal is to test a new theory that links the frictional drag to the spectral exponent , a property of the velocity fluctuations in a flow. We use a soap-film channel wherein for the first time the value of can be switched between 3 and , the two theoretically possible values in soap-film flows. To induce turbulence with , we make one of the edges of the soap-film channel serrated. Remarkably, the new theory of the frictional drag holds in both soap-film flows (for either value of the spectral exponent ) and ordinary pipe flows (where ), even though these types of flow are governed by different equations.
- Received 6 April 2012
DOI:https://doi.org/10.1103/PhysRevLett.109.254502
© 2012 American Physical Society