The linear stability of slip channel flows

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

doi:10.1063/5.0098609

Cited by 11 publications

(3 citation statements)

References 27 publications

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“…In the following investigation, surface slip is modelled using a spatially homogeneous Navier (Robin) slip boundary condition [36], u = g(x, λ) ∂u ∂n and u ⊥ = 0, where u and u ⊥ represent the respective tangential and wall-normal velocities over the surface [37,38]. The function g(x, λ) models slip across the length of the flat plate and surface deformations, while n denotes the normal to the wall.…”

Section: Introductionmentioning

confidence: 99%

Dynamics and control of separated flow over small-scale surface deformations with slip

Ceccacci,

Calabretto,

Thomas

et al. 2024

Phys. Rev. Fluids

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Surface slip was employed to control flow separation induced by small-scale Gaussian-shaped surface deformations on a two-dimensional flat plate. Single surface deformations, including bumps and gaps, were modelled, which generated separated flow along the rear side of the bump and within the gap concavity for a Reynolds number Re = 100 000 when the plate surface was subject to the no-slip condition. Surface slip was modelled using a Navier-slip condition and quantified by a slip length, λ. Bump deformations had a greater impact on the flow dynamics than gap concavities, generating more intense regions of reversed flow and requiring larger slip lengths to inhibit flow separation. In addition, double-bump configurations were modelled, with the location of the two bumps playing a critical role in the evolution of the flow. When the bumps were close together, the first bump controlled the size of the separation bubble that developed downstream of the second bump. Whereas when bumps were far apart, a moderate slip length, λ, excited nonlinear oscillatory flow, reminiscent of the low-frequency flapping observed in previous studies [1][2][3]. However, increasing the slip length suppressed this phenomenon and ultimately eliminated all pockets of separated flow.

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Section: Introductionmentioning

confidence: 99%

Dynamics and control of separated flow over small-scale surface deformations with slip

Ceccacci,

Calabretto,

Thomas

et al. 2024

Phys. Rev. Fluids

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“…Nguyen et al (2021) considered the flow through a channel with square bars and achieved separation drag reduction via a spanwise oscillating pressure gradient. In addition, slip surfaces have proven to be effective in delaying laminar-turbulent transition in channel flows (Lauga and Cossu, 2005;Min and Kim, 2004;Ceccacci et al, 2022b) and favourably control flow separation and reduce drag (Daniello et al, 2009;Fairhall et al, 2019;Mollicone et al, 2022). Ceccacci et al (2022a) recently undertook a numerical study of the two-dimensional flow through a channel with a bump along the lower wall and used a slippery surface to inhibit flow separation.…”

Section: Introductionmentioning

confidence: 99%

Two-dimensional flow over a smooth depression in a channelwith a slip wall

Ceccacci

Calabretto

Thomas

et al. 2023

Preprint

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The effect of slip along a Gaussian-shaped gap deformity, located about a fixed position on the lower wall of a two-dimensional channel, is numerically investigated. Two gap deformations are modelled, with dimensions sufficient to generate localised pockets of reversed flow when the channel walls are fully no-slip. The Reynolds number of the flow, based on the channel half-width, is 4000 for this investigation. The two gap deformations have the same depth, 𝑑, but different widths, 𝜎, leading to a wide gap with an aspect ratio 𝜂 = 𝑑/𝜎 = 0.4 and a narrow gap with an aspect ratio 𝜂 = 0.8. The wide gap establishes a higher intensity region of separated flow within the deformation than the narrow gap. Surface slip with slip length, 𝜆, is modelled via a Robin-type slip boundary condition. Applying the slip condition to the gap concavity reduces the intensity and thickness of the separation bubble within the deformation. Eventually, slip eliminates flow separation altogether for slip lengths 𝜆 = 0.15 and 𝜆 = 0.1 for the wide and narrow gaps, respectively.

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“…Among them, references [9][10][11][12] in particular demonstrated how this simplification may be used to solve issues involving linear stability and transition. According to a few research [13], velocity slip stabilizes the flow and significantly raises the critical Reynolds number when it comes to the linear stability study of slip channel flow.…”

Section: Introductionmentioning

confidence: 99%

Hydrodynamic Stability Analysis for MHD Casson Fluid Flow through a Restricted Channel

Adesanya

Yusuf

Adeosun

et al. 2023

DDF

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Flow instability is a major challenge experienced in medical, engineering and industrial settings globally. For instance, flow instability linked with irregular cardiac output of the heart leads to organ malfunctioning in the medical field, it also encourages mechanical vibrations in the case of fluctuating flow rate, and several other applications. In this study, linear stability analysis is conducted to monitor the behavior of a small disturbance that is imposed on hydromagnetic Casson fluid that flows steadily through a saturated porous medium. A new variant of the Orr-Sommerfield equation is obtained and solved numerically by using spectral point collocation weighted residual approach with eigenfunction expansion of the Chebyshev polynomial as the admissible trial function. Based on the QZ algorithm, numerical results are obtained for wave and Reynold’s numbers, wave velocity as functions of Magnetic field intensity and porosity shape parameters. Results are validated against previously released data. The biophysics of the heart, particularly in cardiac rhythm analysis, as well as several other medicinal and technical applications, is among the areas where the current work has applicability.

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The linear stability of slip channel flows

Cited by 11 publications

References 27 publications

Dynamics and control of separated flow over small-scale surface deformations with slip

Dynamics and control of separated flow over small-scale surface deformations with slip

Two-dimensional flow over a smooth depression in a channelwith a slip wall

Hydrodynamic Stability Analysis for MHD Casson Fluid Flow through a Restricted Channel

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