Article ID Journal Published Year Pages File Type
5006821 Measurement 2017 25 Pages PDF
Abstract
The onset of transition in laminar pulsatile pipe flow can be retarded up to Reta,crit = 4817 at ω′ = 3.85 in the covered experimental range. No more effect of A1 on Reta,crit is seen for ω′ > 8.61 although there is a considerable effect of A1 on Reos,crit. The effect of ω′ on Reta,crit and Reos,crit is not observed for A1 < 0.30. The interactive influences of ω′ and A1 are also investigated on Reta,crit as functions of Reta,crit = Reta,crit (A1ω′) and Reta,crit = Reta,crit (ω′/A1). The interactive influences of ω′ and A1 are not seen on Reta,crit for ω′ > 8.61. This shows that the time-periodicity (ω′, A1) does not affect significantly the onset of transition at the beginning of inertia dominant region of pulsatile laminar flow (ω′ > 8.61) when compared with their interactive effects in the quasi-steady and intermediate regions (ω′ ⩽ 8.61). For flow classification of pulsatile flow at the onset of transition, a new non-dimensional interactive oscillation number, Ios=ω′/A1 is proposed. According to this non-dimensional number, the pulsatile flow at the onset of transition can be subclassified such as quasi-steady for Ios < 5, intermediate for 5 ⩽ Ios ⩽ 30 and inertia dominant regions of pulsatile pipe flows for Ios > 30 considering the effects of both ω′ and A1 on contrary to the classifications available in the literature.
Related Topics
Physical Sciences and Engineering Engineering Control and Systems Engineering
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