The effect of slip on the development of flow separation due to a bump in a channel

Silvia Ceccacci; Sophie A. W. Calabretto; Christian Thomas; James P. Denier

doi:10.1017/jfm.2022.863

The effect of slip on the development of flow separation due to a bump in a channel

Silvia Ceccacci, Sophie A. W. Calabretto, Christian Thomas, James P. Denier

School of Mathematical and Physical Sciences

Research output: Contribution to journal › Article › peer-review

7 Citations (Scopus)

68 Downloads (Pure)

Abstract

A numerical study on the effect of surface slip on the flow in a constricted channel is presented, with the aim of exploring the use of surface slip to control flow separation. Our focus is on two-dimensional flow in a channel over a bump, with a fixed aspect ratio, upon which a Robin-type slip boundary condition is imposed. When the channel walls are fully no-slip, such a flow is known to develop a region of separation behind the bump, at sufficiently large Reynolds numbers. The effect of slip on the separation bubble dynamics occurring behind the bump is investigated, for Reynolds numbers 2000 and 4000. It is shown that surface slip (i) attenuates the intensity of separation as it diminishes the
minimum of the streamwise velocity within the recirculation region; (ii) delays the onset of flow separation, shifting it downstream, along the bump, and (iii) reduces the dimensions of the separation bubble behind the bump, allowing the flow to reattach sooner. Ultimately, slip inhibits separation, with both the points of separation and reattachment coalescing, for a slip length λ of approximately 0.2.

Original language	English
Article number	A31
Pages (from-to)	A31-1-A31-20
Number of pages	20
Journal	Journal of Fluid Mechanics
Volume	951
DOIs	https://doi.org/10.1017/jfm.2022.863
Publication status	Published - 25 Nov 2022

Bibliographical note

© The Author(s), 2022. Published by Cambridge University Press. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

channel flow
separated flows
computational methods

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10.1017/jfm.2022.863Licence: CC BY

Publisher version (open access)Final published version, 3.37 MBLicence: CC BY

Cite this

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abstract = "A numerical study on the effect of surface slip on the flow in a constricted channel is presented, with the aim of exploring the use of surface slip to control flow separation. Our focus is on two-dimensional flow in a channel over a bump, with a fixed aspect ratio, upon which a Robin-type slip boundary condition is imposed. When the channel walls are fully no-slip, such a flow is known to develop a region of separation behind the bump, at sufficiently large Reynolds numbers. The effect of slip on the separation bubble dynamics occurring behind the bump is investigated, for Reynolds numbers 2000 and 4000. It is shown that surface slip (i) attenuates the intensity of separation as it diminishes theminimum of the streamwise velocity within the recirculation region; (ii) delays the onset of flow separation, shifting it downstream, along the bump, and (iii) reduces the dimensions of the separation bubble behind the bump, allowing the flow to reattach sooner. Ultimately, slip inhibits separation, with both the points of separation and reattachment coalescing, for a slip length λ of approximately 0.2.",

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AU - Thomas, Christian

AU - Denier, James P.

N1 - © The Author(s), 2022. Published by Cambridge University Press. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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Y1 - 2022/11/25

N2 - A numerical study on the effect of surface slip on the flow in a constricted channel is presented, with the aim of exploring the use of surface slip to control flow separation. Our focus is on two-dimensional flow in a channel over a bump, with a fixed aspect ratio, upon which a Robin-type slip boundary condition is imposed. When the channel walls are fully no-slip, such a flow is known to develop a region of separation behind the bump, at sufficiently large Reynolds numbers. The effect of slip on the separation bubble dynamics occurring behind the bump is investigated, for Reynolds numbers 2000 and 4000. It is shown that surface slip (i) attenuates the intensity of separation as it diminishes theminimum of the streamwise velocity within the recirculation region; (ii) delays the onset of flow separation, shifting it downstream, along the bump, and (iii) reduces the dimensions of the separation bubble behind the bump, allowing the flow to reattach sooner. Ultimately, slip inhibits separation, with both the points of separation and reattachment coalescing, for a slip length λ of approximately 0.2.

AB - A numerical study on the effect of surface slip on the flow in a constricted channel is presented, with the aim of exploring the use of surface slip to control flow separation. Our focus is on two-dimensional flow in a channel over a bump, with a fixed aspect ratio, upon which a Robin-type slip boundary condition is imposed. When the channel walls are fully no-slip, such a flow is known to develop a region of separation behind the bump, at sufficiently large Reynolds numbers. The effect of slip on the separation bubble dynamics occurring behind the bump is investigated, for Reynolds numbers 2000 and 4000. It is shown that surface slip (i) attenuates the intensity of separation as it diminishes theminimum of the streamwise velocity within the recirculation region; (ii) delays the onset of flow separation, shifting it downstream, along the bump, and (iii) reduces the dimensions of the separation bubble behind the bump, allowing the flow to reattach sooner. Ultimately, slip inhibits separation, with both the points of separation and reattachment coalescing, for a slip length λ of approximately 0.2.

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The effect of slip on the development of flow separation due to a bump in a channel

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