Print Email Facebook Twitter An experimental study of transitional pulsatile pipe flow Title An experimental study of transitional pulsatile pipe flow Author Trip, R. Kuik, D.J. Westerweel, J. Poelma, C. Faculty Mechanical, Maritime and Materials Engineering Department Process and Energy Date 2012-01-06 Abstract The transitional regime of a sinusoidal pulsatile flow in a straight, rigid pipe is investigated using particle image velocimetry. The main aim is to investigate how the critical Reynolds number is affected by different pulsatile conditions, expressed as the Womersley number and the oscillatory Reynolds number. The transition occurs in the region of Re?=?2250-3000 and is characterized by an increasing number of isolated turbulence structures. Based on velocity fields and flow visualizations, these structures can be identified as puffs, similar to those observed in steady flow transition. Measurements at different Womersley numbers yield similar transition behavior, indicating that pulsatile effects do not play a role in the regime that is investigated. Variations of the oscillatory Reynolds number also appear to have little effect, so that the transition here seems to be determined only by the mean Reynolds number. For larger mean Reynolds numbers, a second regime is observed: here, the flow remains turbulent throughout the cycle. The turbulence intensity varies during the cycle, but has a phase shift with respect to the mean flow component. This is caused by a growth of kinetic energy during the decelerating part and a decay during the accelerating part of the cycle. Flow visualization experiments reveal that the flow develops localized turbulence at several random axial positions. The structures quickly grow to fill the entire pipe in the decelerating phase and (partially) decay during the accelerating phase. Subject flow visualisationfluid oscillationslaminar to turbulent transitionspipe flowpulsatile flowturbulence To reference this document use: http://resolver.tudelft.nl/uuid:9474c415-f726-48ed-ae85-91cfe103b5bb DOI https://doi.org/10.1063/1.3673611 Publisher American Institute of Physics ISSN 1070-6631 Source http://link.aip.org/link/doi/10.1063/1.3673611 Source Physics of Fluids, 24 (1), 2012 Part of collection Institutional Repository Document type journal article Rights (c) 2012 The Author(s)American Institute of Physics Files PDF PhysFluids_24_0141031.pdf 1.44 MB Close viewer /islandora/object/uuid:9474c415-f726-48ed-ae85-91cfe103b5bb/datastream/OBJ/view