Abstract
| Original language | English |
|---|---|
| Title of host publication | 43rd Fluid Dynamics Conference, Fluid Dynamics and Co-located Conferences |
| Publisher | Aerospace Research Central |
| Number of pages | 17 |
| ISBN (Electronic) | 9781624102141 |
| DOIs | |
| Publication status | Published - 2013 |
| Externally published | Yes |
| Event | 43rd Fluid Dynamics Conference, Fluid Dynamics and Co-located Conferences - San Diego, United States Duration: 24 Jun 2013 → 27 Jun 2013 |
Conference
| Conference | 43rd Fluid Dynamics Conference, Fluid Dynamics and Co-located Conferences |
|---|---|
| Abbreviated title | AIAA |
| Country | United States |
| City | San Diego |
| Period | 24/06/13 → 27/06/13 |
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The effect of wavepacket frequency bandwidth on the laminar-turbulent transition process in a Blasius boundary layer. / Kang, Kean Lee; Yeo, K. S.
43rd Fluid Dynamics Conference, Fluid Dynamics and Co-located Conferences. Aerospace Research Central, 2013.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
TY - GEN
T1 - The effect of wavepacket frequency bandwidth on the laminar-turbulent transition process in a Blasius boundary layer
AU - Kang, Kean Lee
AU - Yeo, K. S.
PY - 2013
Y1 - 2013
N2 - The subharmonic mode is known to play an important role in a regime of boundary layer transition known as the N (Novosibirsk) or H (Herbert) type. However, until recently, an explanation for its mechanism of production from an input pulse disturbance was lacking. While it is well-known that the subharmonic mode can be amplified by triad resonance interactions, this resonance process is only able to amplify a mode that is already present, but does not show how the mode was initiated or seeded even when it was not present in the initial disturbance pulse. Subsequent researchers have proposed that nonlinear self-interaction among component modes of a wavepacket can generate the subharmonic wave in a wavepacket evolving in a low-speed Blasius boundary layer flow. This hypothesis was tested and verified in experiments, but to date little numerical work had been done. This paper aims to fill in this gap by performing direct numerical simulations (DNS) to gain a better understanding of the process of subharmonic mode generation. The theory predicts the development of the subharmonic to be contingent on the frequency bandwidth of the input disturbance. Indeed, it was found that wide bandwidth signals caused the wavepacket to transition to turbulence via the subharmonic route, whereas narrow bandwidth led to transition through Klebanoff modes (streaks). An interesting hybrid transition scenario was also investigated, in which an intermediate bandwidth input gave rise to wavepacket evolution displaying features of both Klebanoff and subharmonic transition regimes. Furthermore, in any particular transition regime, traces of the other transition mechanisms were uncovered, suggesting that there is competition among the various mechanisms, with the frequency bandwidth being an important factor in determining the path to transition.
AB - The subharmonic mode is known to play an important role in a regime of boundary layer transition known as the N (Novosibirsk) or H (Herbert) type. However, until recently, an explanation for its mechanism of production from an input pulse disturbance was lacking. While it is well-known that the subharmonic mode can be amplified by triad resonance interactions, this resonance process is only able to amplify a mode that is already present, but does not show how the mode was initiated or seeded even when it was not present in the initial disturbance pulse. Subsequent researchers have proposed that nonlinear self-interaction among component modes of a wavepacket can generate the subharmonic wave in a wavepacket evolving in a low-speed Blasius boundary layer flow. This hypothesis was tested and verified in experiments, but to date little numerical work had been done. This paper aims to fill in this gap by performing direct numerical simulations (DNS) to gain a better understanding of the process of subharmonic mode generation. The theory predicts the development of the subharmonic to be contingent on the frequency bandwidth of the input disturbance. Indeed, it was found that wide bandwidth signals caused the wavepacket to transition to turbulence via the subharmonic route, whereas narrow bandwidth led to transition through Klebanoff modes (streaks). An interesting hybrid transition scenario was also investigated, in which an intermediate bandwidth input gave rise to wavepacket evolution displaying features of both Klebanoff and subharmonic transition regimes. Furthermore, in any particular transition regime, traces of the other transition mechanisms were uncovered, suggesting that there is competition among the various mechanisms, with the frequency bandwidth being an important factor in determining the path to transition.
U2 - 10.2514/6.2013-2615
DO - 10.2514/6.2013-2615
M3 - Conference contribution
BT - 43rd Fluid Dynamics Conference, Fluid Dynamics and Co-located Conferences
PB - Aerospace Research Central
ER -