Receptivity and Instability : Role of Spatio-Temporal Wave Front In Transition
Event details
| Date | 23.02.2016 |
| Hour | 11:15 › 12:15 |
| Speaker | Prof. Tapan K. Sengupta |
| Location | |
| Category | Conferences - Seminars |
To understand the unit process(es) of transition to turbulence via two- and three-dimensional routes of low amplitude disturbance growth over a zero pressure gradient boundary layer (ZPG-BL) remains the canonical problem. There are numerous attempts to understand the process for ZPG-BL. In the present talk, results obtained from solutions of Navier-Stokes equation and its linearized parallel flow version will be presented which reproduce classical experiment of Schubauer-Skramstad (1947). The experiments used low disturbance tunnel at NBS and imposed deterministic harmonic excitation inside the shear layer. This scenario was studied in Sengupta and Bhaumik [Phys. Rev. Lett. 107, 154501 (2011)], where a route of transition to fully developed turbulent stage was explained for 2D disturbances in terms of the spatio-temporal wave-front (STWF). The STWF was earlier identified as the unit process by theoretical receptivity solution of Orr-Sommerfeld equation by Bromwich contour integral method in Sengupta et al. [Phys. Rev. Lett. 96, 224504 (2006)] as due to spatiotemporal instability. Of late, we have reported the same process of the STWF for transition involving 3D disturbance field from DNS. These findings show the importance of STWF over Tollmien-Schlichting waves, which was considered central for flow transition by low amplitude disturbances.
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Practical information
- General public
- Free
Organizer
- Laboratory of Fluid Mechanics and Instabilities (LFMI)
Contact
- Prof. François Gallaire