Pressure-Induced Separation of a Laminar Boundary Layer over a Partially-Slip Wall
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| Format: | Preprint |
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2024
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| _version_ | 1866916355850108928 |
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| author | Cooper, Benjamin Kellum Savino, Benjamin S. Cooper, John Marshall Yeom, Taiho Wu, Wen |
| author_facet | Cooper, Benjamin Kellum Savino, Benjamin S. Cooper, John Marshall Yeom, Taiho Wu, Wen |
| contents | The characteristics of pressure-induced laminar separation bubbles (LSBs) over a partially-slip wall, compared with that over a canonical no-slip wall, are studied using direct numerical simulation. Three cases, two utilizing linear Robin-type slip boundary conditions of differing slip length ($Λ$), and one non-slip are compared. For the partial-slip cases, a streamwise distribution of slip profile is employed ensuring smooth transition between no-slip and partial-slip (transition from no-slip to a constant slip length takes 5$δ$, where $δ$ is the inflow boundary layer thickness). The constant target slip length is maintained for $20δ$ upstream and during the onset of flow separation. The separation is induced by a wall-normal velocity profile applied at the top boundary. All cases are performed at $Re_δ= U_{\infty}δ/ν= 455$. Initial results indicate that as slip length increases, separation and reattachment are delayed. Most notably, the formation and shedding of roller vortices is mitigated as slip length increases, resulting in a less turbulent wake, despite that self-similarity of the plane shear layer is maintained. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2408_07008 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Pressure-Induced Separation of a Laminar Boundary Layer over a Partially-Slip Wall Cooper, Benjamin Kellum Savino, Benjamin S. Cooper, John Marshall Yeom, Taiho Wu, Wen Fluid Dynamics The characteristics of pressure-induced laminar separation bubbles (LSBs) over a partially-slip wall, compared with that over a canonical no-slip wall, are studied using direct numerical simulation. Three cases, two utilizing linear Robin-type slip boundary conditions of differing slip length ($Λ$), and one non-slip are compared. For the partial-slip cases, a streamwise distribution of slip profile is employed ensuring smooth transition between no-slip and partial-slip (transition from no-slip to a constant slip length takes 5$δ$, where $δ$ is the inflow boundary layer thickness). The constant target slip length is maintained for $20δ$ upstream and during the onset of flow separation. The separation is induced by a wall-normal velocity profile applied at the top boundary. All cases are performed at $Re_δ= U_{\infty}δ/ν= 455$. Initial results indicate that as slip length increases, separation and reattachment are delayed. Most notably, the formation and shedding of roller vortices is mitigated as slip length increases, resulting in a less turbulent wake, despite that self-similarity of the plane shear layer is maintained. |
| title | Pressure-Induced Separation of a Laminar Boundary Layer over a Partially-Slip Wall |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2408.07008 |