Response maxima in timemodulated turbulence: Direct numerical simulations
Abstract
The response of turbulent flow to timemodulated forcing is studied by direct numerical simulations of the NavierStokes equations. The largescale forcing is modulated via periodic energy input variations at frequency ω. The response is maximal for frequencies in the range of the inverse of the large eddy turnover time, confirming the meanfield predictions of von der Heydt, Grossmann and Lohse (Phys. Rev. E, 67 (2003) 046308). In accordance with the theory the response maximum shows only a small dependence on the Reynolds number. At sufficiently high frequencies the amplitude of the kinetic energy response decreases as 1/ω. For frequencies beyond the range of maximal response, a significant change in the phaseshift relative to the timemodulated forcing is observed. For large ω the phase shift approaches roughly 90° for the total energy and 180° for the energy dissipation rate.
 Publication:

EPL (Europhysics Letters)
 Pub Date:
 March 2006
 DOI:
 10.1209/epl/i2005104862
 arXiv:
 arXiv:physics/0509208
 Bibcode:
 2006EL.....73..851K
 Keywords:

 47.27.Rc;
 47.27.E;
 47.27.Gs;
 Turbulence control;
 Turbulence simulation and modeling;
 Isotropic turbulence;
 homogeneous turbulence;
 Fluid Dynamics;
 Computational Physics
 EPrint:
 submitted to Europhysics Letters (EPL), 8 pages, 8 Postscript figures, uses epl.cls