A discussion of fraud number applicability for description of self-aerated developing open channel flows

Wangru Wei, Jun Deng

Thursday 2 july 2015

16:00 - 16:15h at South America (level 0)

Themes: (T) Water engineering, (ST) River and coastal engineering

Parallel session: 13C. Engineering - Industrial

Air bubble diffusion in the self-aerated open channel flows is an essential issue, and the development process is affected by the approach flow characteristics. The flow Froude number was generally used as the hydraulic condition in previous investigations to study the air transport in uniform air-water flows. However, few of these studies analyzed the applicability of Froude number in self-aerated developing region. The present investigation systematically model-tested development of self-aeration diffusion with various approach flow Froude number. The tests results showed that for the tests under same Froude number condition, the air bubble diffusions are not coincident and no clear trend of the Froude number effect is observed. Considering that flow Froude number is the factor of flow status: supercritical flow or subcritical flow, Froude number should not be considered as hydraulic condition for description of air bubble diffusion in self-aerated developing region. It was demonstrated that the flow status generally misestimates the self-aerated process in developing open channel flows.