File Download

There are no files associated with this item.

  • Find it @ UNIST can give you direct access to the published full text of this article. (UNISTARs only)
Related Researcher


Kim, Jooha
Read More

Views & Downloads

Detailed Information

Cited time in webofscience Cited time in scopus
Metadata Downloads

Full metadata record

DC Field Value Language
dc.citation.number 1 -
dc.citation.startPage 015107 -
dc.citation.title PHYSICS OF FLUIDS -
dc.citation.volume 31 - Chae, Seokbong - Lee, Seungcheol - Kim, Jooha - Lee, Jae Hwa - 2023-12-21T19:43:05Z - 2023-12-21T19:43:05Z - 2019-01-22 - 2019-01 -
dc.description.abstract A new adaptive-passive control device is introduced to optimally reduce the drag on a sphere over a wide range of Reynolds numbers, Re = 0.4 × 105-4.4 × 105. The device, called an adaptive moving ring (AMR), is designed to change its size (i.e., protrusion height) adaptively depending on the wind speed (i.e., the Reynolds number) without energy input. An empirical model is formulated to accurately predict the drag coefficient as a function of the size of AMR and the Reynolds number. Based on the model, we estimate how the optimal size of AMR should vary with the Reynolds number to maximize the drag reduction. Following the estimation of the optimal size, the optimally tuned AMR reduces its protrusion height with increasing Reynolds number, and the drag decreases monotonically by up to 74% compared to that of a smooth sphere. The drag reduction by AMR is attributed to different mechanisms depending on the Reynolds number. For low Reynolds numbers, the locally separated flow at large AMR is energized by the disturbance induced by AMR and reattaches to the sphere surface, forming a large recirculation region. Then, the main separation is delayed downstream due to the increased near-wall momentum. On the other hand, at high Reynolds numbers, no recirculation zone is formed at AMR due to its low protrusion height, but a secondary separation bubble is generated on the rear sphere surface. Therefore, the boundary-layer flow becomes turbulent, and the main separation is significantly delayed, resulting in more drag reduction than for low Reynolds numbers. -
dc.identifier.bibliographicCitation PHYSICS OF FLUIDS, v.31, no.1, pp.015107 -
dc.identifier.doi 10.1063/1.5063908 -
dc.identifier.issn 1070-6631 -
dc.identifier.scopusid 2-s2.0-85060144086 -
dc.identifier.uri -
dc.identifier.url -
dc.identifier.wosid 000457470800045 -
dc.language 영어 -
dc.publisher AMER INST PHYSICS -
dc.title Adaptive-passive control of flow over a sphere for drag reduction -
dc.type Article -
dc.description.isOpenAccess FALSE -
dc.relation.journalWebOfScienceCategory Mechanics; Physics, Fluids & Plasmas -
dc.relation.journalResearchArea Mechanics; Physics -
dc.description.journalRegisteredClass scie -
dc.description.journalRegisteredClass scopus -
dc.subject.keywordPlus LAMINAR SEPARATION BUBBLE -
dc.subject.keywordPlus PIV MEASUREMENTS -
dc.subject.keywordPlus GOLF BALL -
dc.subject.keywordPlus AERODYNAMICS -
dc.subject.keywordPlus ROUGHNESS -


Items in Repository are protected by copyright, with all rights reserved, unless otherwise indicated.