Linear stability of confined flow around a 180-degree sharp bend
This study seeks to characterise the breakdown of the steady two-dimensional solution in the flow around a 180-degree sharp bend to infinitesimal three-dimensional disturbances using a linear stability analysis. The stability analysis predicts that three-dimensional transition is via a synchronou...
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| Format: | Article |
| Language: | English English |
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Cambridge University Press
2017
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| Subjects: | |
| Online Access: | http://irep.iium.edu.my/79094/ http://irep.iium.edu.my/79094/1/SapardiHussamPotheratSheard_JFM2017.pdf http://irep.iium.edu.my/79094/13/79094%20Linear%20stability%20of%20confined%20flow%20%20SCOPUS.pdf |
| _version_ | 1848788717839319040 |
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| author | Mohammed Sapardi, Mohd Azan Hussam, Wisam K. Potherat, Alban Sheard, Gregory J. |
| author_facet | Mohammed Sapardi, Mohd Azan Hussam, Wisam K. Potherat, Alban Sheard, Gregory J. |
| author_sort | Mohammed Sapardi, Mohd Azan |
| building | IIUM Repository |
| collection | Online Access |
| description | This study seeks to characterise the breakdown of the steady two-dimensional solution
in the flow around a 180-degree sharp bend to infinitesimal three-dimensional
disturbances using a linear stability analysis. The stability analysis predicts that
three-dimensional transition is via a synchronous instability of the steady flows.
A highly accurate global linear stability analysis of the flow was conducted with
Reynolds number Re < 1150 and bend opening ratio (ratio of bend width to inlet
height) 0.26β 65. This range of Re and β captures both steady-state two-dimensional
flow solutions and the inception of unsteady two-dimensional flow. For 0.2 6 β 6 1,
the two-dimensional base flow transitions from steady to unsteady at higher Reynolds
number as β increases. The stability analysis shows that at the onset of instability,
the base flow becomes three-dimensionally unstable in two different modes, namely
a spanwise oscillating mode for β = 0.2 and a spanwise synchronous mode for
β > 0.3. The critical Reynolds number and the spanwise wavelength of perturbations
increase as β increases. For 1 < β 6 2 both the critical Reynolds number for onset
of unsteadiness and the spanwise wavelength decrease as β increases. Finally, for
2 < β 6 5, the critical Reynolds number and spanwise wavelength remain almost
constant. The linear stability analysis also shows that the base flow becomes unstable
to different three-dimensional modes depending on the opening ratio. The modes are
found to be localised near the reattachment point of the first recirculation bubble |
| first_indexed | 2025-11-14T17:45:16Z |
| format | Article |
| id | iium-79094 |
| institution | International Islamic University Malaysia |
| institution_category | Local University |
| language | English English |
| last_indexed | 2025-11-14T17:45:16Z |
| publishDate | 2017 |
| publisher | Cambridge University Press |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | iium-790942020-04-03T04:52:54Z http://irep.iium.edu.my/79094/ Linear stability of confined flow around a 180-degree sharp bend Mohammed Sapardi, Mohd Azan Hussam, Wisam K. Potherat, Alban Sheard, Gregory J. TJ Mechanical engineering and machinery This study seeks to characterise the breakdown of the steady two-dimensional solution in the flow around a 180-degree sharp bend to infinitesimal three-dimensional disturbances using a linear stability analysis. The stability analysis predicts that three-dimensional transition is via a synchronous instability of the steady flows. A highly accurate global linear stability analysis of the flow was conducted with Reynolds number Re < 1150 and bend opening ratio (ratio of bend width to inlet height) 0.26β 65. This range of Re and β captures both steady-state two-dimensional flow solutions and the inception of unsteady two-dimensional flow. For 0.2 6 β 6 1, the two-dimensional base flow transitions from steady to unsteady at higher Reynolds number as β increases. The stability analysis shows that at the onset of instability, the base flow becomes three-dimensionally unstable in two different modes, namely a spanwise oscillating mode for β = 0.2 and a spanwise synchronous mode for β > 0.3. The critical Reynolds number and the spanwise wavelength of perturbations increase as β increases. For 1 < β 6 2 both the critical Reynolds number for onset of unsteadiness and the spanwise wavelength decrease as β increases. Finally, for 2 < β 6 5, the critical Reynolds number and spanwise wavelength remain almost constant. The linear stability analysis also shows that the base flow becomes unstable to different three-dimensional modes depending on the opening ratio. The modes are found to be localised near the reattachment point of the first recirculation bubble Cambridge University Press 2017-07-10 Article PeerReviewed application/pdf en http://irep.iium.edu.my/79094/1/SapardiHussamPotheratSheard_JFM2017.pdf application/pdf en http://irep.iium.edu.my/79094/13/79094%20Linear%20stability%20of%20confined%20flow%20%20SCOPUS.pdf Mohammed Sapardi, Mohd Azan and Hussam, Wisam K. and Potherat, Alban and Sheard, Gregory J. (2017) Linear stability of confined flow around a 180-degree sharp bend. Journal of Fluid Mechanics, 822. pp. 813-847. ISSN 0022-1120 E-ISSN 1469-7645 https://www.cambridge.org/core/journals/journal-of-fluid-mechanics 10.1017/jfm.2017.266 |
| spellingShingle | TJ Mechanical engineering and machinery Mohammed Sapardi, Mohd Azan Hussam, Wisam K. Potherat, Alban Sheard, Gregory J. Linear stability of confined flow around a 180-degree sharp bend |
| title | Linear stability of confined flow around a 180-degree sharp bend |
| title_full | Linear stability of confined flow around a 180-degree sharp bend |
| title_fullStr | Linear stability of confined flow around a 180-degree sharp bend |
| title_full_unstemmed | Linear stability of confined flow around a 180-degree sharp bend |
| title_short | Linear stability of confined flow around a 180-degree sharp bend |
| title_sort | linear stability of confined flow around a 180-degree sharp bend |
| topic | TJ Mechanical engineering and machinery |
| url | http://irep.iium.edu.my/79094/ http://irep.iium.edu.my/79094/ http://irep.iium.edu.my/79094/ http://irep.iium.edu.my/79094/1/SapardiHussamPotheratSheard_JFM2017.pdf http://irep.iium.edu.my/79094/13/79094%20Linear%20stability%20of%20confined%20flow%20%20SCOPUS.pdf |