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Memorias de investigación
Artículos en revistas:
Estimation of turbulent convection velocities and corrections to Taylor's approximation
Año:2009
Áreas de investigación
  • Mecánica de fluidos
Datos
Descripción
A new method is introduced for estimating the convection velocity of individual modes in turbulent shear flows that, in contrast to most previous ones, only requires spectral information in the temporal or spatial direction over which a modal decomposition is desired, while only using local derivatives in other directions. If no spectral information is desired, the method provides a natural definition for the average convection velocity, as well as a way to estimate the accuracy of the frozen-turbulence approximation. Existing data from numerical turbulent channels at friction Reynolds numbers Re¿ T 1900 are used to validate the new method against classical ones, and to characterize the dependence of the convection velocity on the eddy wavelength and wall distance. The results indicate that the small scales in turbulent channels travel at the local mean velocity, while large `global¿ modes travel at a more uniform speed proportional to the bulk velocity. To estimate the systematic deviations introduced in experimental spectra by the use of Taylor¿s approximation with a wavelength- independent convection velocity, a semi-empirical fit to the computed convection velocities is provided. It represents well the data throughout the Reynolds number range of the simulations. It is shown that Taylor¿s approximation not only displaces the large scales near the wall to shorter apparent wavelengths but also modifies the shape of the spectrum, giving rise to spurious peaks similar to those observed in some experiments. To a lesser extent the opposite is true above the logarithmic layer. The effect increases with the Reynolds number, suggesting that some of the recent challenges to the k¿1 energy spectrum may have to be reconsidered.
Internacional
Si
JCR del ISI
Si
Título de la revista
JOURNAL OF FLUID MECHANICS
ISSN
0022-1120
Factor de impacto JCR
2,315
Información de impacto
Volumen
640
DOI
Número de revista
0
Desde la página
5
Hasta la página
26
Mes
DICIEMBRE
Ranking
Esta actividad pertenece a memorias de investigación
Participantes
  • Autor: Javier Jimenez Sendin (UPM)
Grupos de investigación, Departamentos, Centros e Institutos de I+D+i relacionados
  • Creador: Grupo de Investigación: Mecánica de Fluidos Computacional
  • Departamento: Motopropulsión y Termofluidodinámica
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