| Título: | Turbulent Flow over a Flexible Wall Undergoing a Streamwise Traveling Wavy Motion |
| Autores: |
Shen, Lian Zhang, Xiang Yue, Dick K.P. Triantafyllou, Michael S. |
| Fecha: |
2005-08-23 2005-08-23 2003 |
| Publicador: | MIT |
| Fuente: |
 |
| Tipo: | Article |
| Tema: |
Turbulence reynolds number numerical simulation |
| Descripción: | Direct numerical simulation is used to study the turbulent flow over a smooth wavy wall undergoing transverse motion in the form of a streamwise travelling wave. The Reynolds number based on the mean velocity U of the external flow and wall motion wavelength λ is 10 170; the wave steepness is 2πa/λ = 0.25 where a is the travelling wave amplitude. A key parameter for this problem is the ratio of the wall motion phase speed c to U, and results are obtained for c/U in the range of â1.0 to 2.0 at 0.2 intervals. For negative c/U, we find that flow separation is enhanced and a large drag force is produced. For positive c/U, the results show that as c/U increases from zero, the separation bubble moves further upstream and away from the wall, and is reduced in strength. Above a threshold value of c/U ≈ 1, separation is eliminated; and, relative to small- c/U cases, turbulence intensity and turbulent shear stress are reduced significantly. The drag force decreases monotonically as c/U increases while the power required for the transverse motion generally increases for large c/U; the net power input is found to reach a minimum at c/U ≈ 1.2 (for fixed U). The results obtained in this study provide physical insight into the study of fish-like swimming mechanisms in terms of drag reduction and optimal propulsive efficiency. |
| Idioma: | Inglés |
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