Recent theoretical results are presented from our ongoing study investigating the distinct convective instability properties of the boundary-layer flow over rough rotating disks. In this study, radial anisotropic surface roughness (concentric grooves) is modelled using the partial-slip approach of Miklavčič & Wang (2004) and the surface-geometry approach of Yoon et. al (2007). An energy analysis reveals that for both instability modes, the main contributors to the energy balance are the energy production by the Reynolds stresses and conventional viscous dissipation. For the Type I mode, energy dissipation increases and the Reynolds-stress energy production decreases with roughness under both models. This suggests a clear stabilising effect of the anisotropic roughness on the Type I mode. For the Type II mode, the Reynolds-stress energy production increases with roughness under both models. However, the energy dissipation of the Type II mode decreases with the roughness under the surface-geometry model and increases under the partial-slip model. This sensitivity to the precise form of the anisotropic roughness suggests that maximising dissipation by an appropriately designed roughness can theoretically lead to an overall beneficial stabilisation of both the Type I and Type II modes. This is a potential route to overall boundary-layer-transition delay and drag reduction in cross-flow dominated flows.
|Title of host publication||Open Archives of the 16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2016|
|Publication status||Published - 2019|
|Event||16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2016 - Honolulu, United States|
Duration: 10 Apr 2016 → 15 Apr 2016
|Conference||16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2016|
|Period||10/04/16 → 15/04/16|
Bibliographical noteFunding Information:
SJG is supported by a Senior Research Fellowship of the Royal Academy of Engineering, funded by the Leverhulme Trust. SJG also wishes to acknowledge the hospitality of the Faculty of Science, School of Mathematics at the University of Sydney, Australia where the final version of this paper was completed. MÖ wishes to acknowledge financial support from Republic of Turkey Ministry of National Education.
© Open Archives of the 16th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, ISROMAC 2016. All rights reserved.
- Rotating boundary layers
- Surface Roughness