A non-dimensional oscillation parameter describing interactive influence of oscillation frequency and velocity amplitude ratio for use in pulsatile flows
| Autor: | Emrah Özahi, Melda Ozdinc Carpinlioglu |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Condensed matter physics
Oscillation Applied Mathematics Pulsatile flow Reynolds number Laminar flow 02 engineering and technology Condensed Matter Physics 01 natural sciences 010305 fluids & plasmas Pipe flow symbols.namesake 020303 mechanical engineering & transports Classical mechanics 0203 mechanical engineering Flow (mathematics) Womersley number Velocity amplitude 0103 physical sciences symbols Electrical and Electronic Engineering Instrumentation Mathematics |
| Zdroj: | Measurement. 99:36-43 |
| ISSN: | 0263-2241 |
| DOI: | 10.1016/j.measurement.2016.12.018 |
| Popis: | The interactive influences of oscillation frequency and velocity amplitude ratio on onset of transition in pulsatile pipe flow are investigated experimentally in the ranges of time-averaged and oscillating Reynolds numbers of 1019 ± 35 ⩽ Re ta ⩽ 4817 ± 164 and 107 ± 4 ⩽ Re os ⩽ 4261 ± 145 with velocity amplitude ratio of 0.05 ± 0.0017 ⩽ A 1 ⩽ 0.96 ± 0.03 for 227 runs. Oscillation frequency is in the range of 0.1 Hz ⩽ f ⩽ 14 Hz corresponding to Womersley number range of 2.72 ⩽ ω ′ ⩽ 32.21 covering quasi-steady, intermediate and beginning of inertia dominant regimes of pulsatile laminar flow. The onset of transition in laminar pulsatile pipe flow can be retarded up to Re ta , crit = 4817 at ω ′ = 3.85 in the covered experimental range. No more effect of A 1 on Re ta , crit is seen for ω ′ > 8.61 although there is a considerable effect of A 1 on Re os , crit . The effect of ω ′ on Re ta , crit and Re os , crit is not observed for A 1 ω ′ and A 1 are also investigated on Re ta , crit as functions of Re ta , crit = Re ta , crit ( A 1 ω ′ ) and Re ta , crit = Re ta , crit ( ω ′ / A 1 ). The interactive influences of ω ′ and A 1 are not seen on Re ta , crit for ω ′ > 8.61. This shows that the time-periodicity ( ω ′ , A 1 ) 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, I os = ω ′ / A 1 is proposed. According to this non-dimensional number, the pulsatile flow at the onset of transition can be subclassified such as quasi-steady for I os I os ⩽ 30 and inertia dominant regions of pulsatile pipe flows for I os > 30 considering the effects of both ω ′ and A 1 on contrary to the classifications available in the literature. |
| Databáze: | OpenAIRE |
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