title: An investigation into inflection-point instability in the entrance region of a pulsating pipe flow.
abstract: This paper investigates the inflection-point instability that governs the flow disturbance initiated in the entrance region of a pulsating pipe flow. Under such a flow condition, the flow instability grows within a certain phase region in a pulsating cycle, during which the inflection point in the unsteady mean flow lifts away from the viscous effect-dominated region known as the Stokes layer. The characteristic frequency of the instability is found to be in agreement with that predicted by the mixing-layer model. In comparison with those cases not falling in this category, it is further verified that the flow phenomenon will take place only if the inflection point lifts away sufficiently from the Stokes layer.
authors.affiliation: Department of Aeronautics and Astronautics , National Cheng Kung University , Tainan 70101 , Taiwan, Republic of China.
authors.forename: J J
authors.identifier: 0000-0003-3655-9917
authors.initials: JJ
authors.lastname: Miau
authors.affiliation: Department of Aeronautics and Astronautics , National Cheng Kung University , Tainan 70101 , Taiwan, Republic of China.
authors.forename: R H
authors.initials: RH
authors.lastname: Wang
authors.affiliation: Department of Aeronautics and Astronautics , National Cheng Kung University , Tainan 70101 , Taiwan, Republic of China.
authors.forename: T W
authors.initials: TW
authors.lastname: Jian
authors.affiliation: Department of Aeronautics and Astronautics , National Cheng Kung University , Tainan 70101 , Taiwan, Republic of China.
authors.forename: Y T
authors.initials: YT
authors.lastname: Hsu
keywords: hot-wire measurement; inflection-point instability; pulsating pipe flow; unsteady boundary layer