Stability of a Buoyant Oldroyd-B Flow Saturating a Vertical Porous Layer with Open Boundaries
The performance of several engineering applications are strictly connected to the rheology of the working fluids and the Oldroyd-B model is widely employed to describe a linear viscoelastic behaviour. In the present paper, a buoyant Oldroyd-B flow in a vertical porous layer with permeable and isothe...
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| Format: | Article |
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MDPI AG
2021-10-01
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| Series: | Fluids |
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| Online Access: | https://www.mdpi.com/2311-5521/6/11/375 |
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| author | Stefano Lazzari Michele Celli Antonio Barletta |
| author_facet | Stefano Lazzari Michele Celli Antonio Barletta |
| author_sort | Stefano Lazzari |
| collection | DOAJ |
| description | The performance of several engineering applications are strictly connected to the rheology of the working fluids and the Oldroyd-B model is widely employed to describe a linear viscoelastic behaviour. In the present paper, a buoyant Oldroyd-B flow in a vertical porous layer with permeable and isothermal boundaries is investigated. Seepage flow is modelled through an extended version of Darcy’s law which accounts for the Oldroyd-B rheology. The basic stationary flow is parallel to the vertical axis and describes a single-cell pattern where the cell has an infinite height. A linear stability analysis of such a basic flow is carried out to determine the onset conditions for a multicellular pattern. This analysis is performed numerically by employing the shooting method. The neutral stability curves and the values of the critical Rayleigh number are evaluated for different retardation time and relaxation time characteristics of the fluid. The study highlights the extent to which the viscoelasticity has a destabilising effect on the buoyant flow. For the limiting case of a Newtonian fluid, the known results available in the literature are recovered, namely a critical value of the Darcy–Rayleigh number equal to 197.081 and a corresponding critical wavenumber of 1.05950. |
| first_indexed | 2024-03-10T05:30:50Z |
| format | Article |
| id | doaj.art-b6c2417c29a144648dcb36fd43bdd12e |
| institution | Directory Open Access Journal |
| issn | 2311-5521 |
| language | English |
| last_indexed | 2024-03-10T05:30:50Z |
| publishDate | 2021-10-01 |
| publisher | MDPI AG |
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| series | Fluids |
| spelling | doaj.art-b6c2417c29a144648dcb36fd43bdd12e2023-11-22T23:17:16ZengMDPI AGFluids2311-55212021-10-0161137510.3390/fluids6110375Stability of a Buoyant Oldroyd-B Flow Saturating a Vertical Porous Layer with Open BoundariesStefano Lazzari0Michele Celli1Antonio Barletta2Department of Architecture and Design, University of Genoa, Stradone S. Agostino 37, 16123 Genova, ItalyDepartment of Industrial Engineering, Alma Mater Studiorum-Università di Bologna, Via Risorgimento 2, 40136 Bologna, ItalyDepartment of Industrial Engineering, Alma Mater Studiorum-Università di Bologna, Via Risorgimento 2, 40136 Bologna, ItalyThe performance of several engineering applications are strictly connected to the rheology of the working fluids and the Oldroyd-B model is widely employed to describe a linear viscoelastic behaviour. In the present paper, a buoyant Oldroyd-B flow in a vertical porous layer with permeable and isothermal boundaries is investigated. Seepage flow is modelled through an extended version of Darcy’s law which accounts for the Oldroyd-B rheology. The basic stationary flow is parallel to the vertical axis and describes a single-cell pattern where the cell has an infinite height. A linear stability analysis of such a basic flow is carried out to determine the onset conditions for a multicellular pattern. This analysis is performed numerically by employing the shooting method. The neutral stability curves and the values of the critical Rayleigh number are evaluated for different retardation time and relaxation time characteristics of the fluid. The study highlights the extent to which the viscoelasticity has a destabilising effect on the buoyant flow. For the limiting case of a Newtonian fluid, the known results available in the literature are recovered, namely a critical value of the Darcy–Rayleigh number equal to 197.081 and a corresponding critical wavenumber of 1.05950.https://www.mdpi.com/2311-5521/6/11/375buoyant convectionporous mediumOldroyd-B viscoelastic fluidlinear stability analysisopen boundary |
| spellingShingle | Stefano Lazzari Michele Celli Antonio Barletta Stability of a Buoyant Oldroyd-B Flow Saturating a Vertical Porous Layer with Open Boundaries Fluids buoyant convection porous medium Oldroyd-B viscoelastic fluid linear stability analysis open boundary |
| title | Stability of a Buoyant Oldroyd-B Flow Saturating a Vertical Porous Layer with Open Boundaries |
| title_full | Stability of a Buoyant Oldroyd-B Flow Saturating a Vertical Porous Layer with Open Boundaries |
| title_fullStr | Stability of a Buoyant Oldroyd-B Flow Saturating a Vertical Porous Layer with Open Boundaries |
| title_full_unstemmed | Stability of a Buoyant Oldroyd-B Flow Saturating a Vertical Porous Layer with Open Boundaries |
| title_short | Stability of a Buoyant Oldroyd-B Flow Saturating a Vertical Porous Layer with Open Boundaries |
| title_sort | stability of a buoyant oldroyd b flow saturating a vertical porous layer with open boundaries |
| topic | buoyant convection porous medium Oldroyd-B viscoelastic fluid linear stability analysis open boundary |
| url | https://www.mdpi.com/2311-5521/6/11/375 |
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