Memorias de investigación
Artículos en revistas:
Transient growth analysis of the flow past a circular cylinder
Año:2009
Áreas de investigación
  • Mecánica de fluidos
Datos
Descripción
We apply direct transient growth analysis in complex geometries to investigate its role in the primary and secondary bifurcation/transition process of the flow past a circular cylinder. The methodology is based on the singular value decomposition of the Navier-Stokes evolution operator linearized about a two-dimensional steady or periodic state which leads to the optimal growth modes. Linearly stable and unstable steady flow at Re=45 and 50 is considered first, where the analysis demonstrates that strong two-dimensional transient growth is observed with energy amplifications of order of 10(3) at U-infinity tau/D approximate to 30. Transient growth at Re=50 promotes the linear instability which ultimately saturates into the well known von-Kaacutermaacuten street. Subsequently we consider the transient growth upon the time-periodic base state corresponding to the von-Kaacutermaacuten street at Re=200 and 300. Depending upon the spanwise wavenumber the flow at these Reynolds numbers are linearly unstable due to the so-called mode A and B instabilities. Once again energy amplifications of order of 10(3) are observed over a time interval of tau/T=2, where T is the time period of the base flow shedding. In all cases the maximum energy of the optimal initial conditions are located within a diameter of the cylinder in contrast to the spatial distribution of the unstable eigenmodes which extend far into the downstream wake. It is therefore reasonable to consider the analysis as presenting an accelerator to the existing modal mechanism. The rapid amplification of the optimal growth modes highlights their importance in the transition process for flow past circular cylinder, particularly when comparing with experimental results where these types of convective instability mechanisms are likely to be activated. The spatial localization, close to the cylinder, of the optimal initial condition may be significant when considering strategies to promote or control shedding.
Internacional
Si
JCR del ISI
Si
Título de la revista
PHYSICS OF FLUIDS
ISSN
1070-6631
Factor de impacto JCR
1,738
Información de impacto
Volumen
21
DOI
Número de revista
4
Desde la página
044103-1
Hasta la página
044103-1
Mes
ABRIL
Ranking
Esta actividad pertenece a memorias de investigación
Participantes
  • Participante: Spencer Sherwin Imperial College London
  • Autor: Vassilios Theofilis . UPM
  • Participante: Nadir Abdessemed Imperial College London
Grupos de investigación, Departamentos, Centros e Institutos de I+D+i relacionados
  • Creador: Grupo de Investigación: Mecánica de Fluidos Computacional
  • Departamento: Motopropulsión y Termofluidodinámica