Algebraic disturbance growth by interaction of Orr and lift-up mechanisms
| Autor: | M. J. Philipp Hack, Parviz Moin |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Physics
Parallel flow Mechanical Engineering Reynolds number Mechanics Parameter space Condensed Matter Physics 01 natural sciences 010305 fluids & plasmas Physics::Fluid Dynamics 010101 applied mathematics Lift (mathematics) symbols.namesake Mechanics of Materials 0103 physical sciences Blasius boundary layer symbols Wavenumber 0101 mathematics Algebraic number Pressure gradient |
| Zdroj: | Journal of Fluid Mechanics. 829:112-126 |
| ISSN: | 1469-7645 0022-1120 |
| DOI: | 10.1017/jfm.2017.557 |
| Popis: | Algebraic disturbance growth in spatially developing boundary-layer flows is investigated using an optimization approach. The methodology builds on the framework of the parabolized stability equations and avoids some of the limitations associated with adjoint-based schemes. In the Blasius boundary layer, non-parallel effects are shown to significantly enhance the energy gain due to algebraic growth mechanisms. In contrast to parallel flow, the most energetic perturbations have finite frequency and are generated by the simultaneous activity of the Orr and lift-up mechanisms. The highest amplification occurs in a limited region of the parameter space that is characterized by a linear relation between the wavenumber and frequency of the disturbances. The frequency of the most highly amplified perturbations decreases with Reynolds number. Adverse streamwise pressure gradient further enhances the amplification of disturbances while preserving the linear trend between the wavenumber and frequency of the most energetic perturbations. |
| Databáze: | OpenAIRE |
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