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Phys. Fluids 13, 3783 (2001); http://dx.doi.org/10.1063/1.1412246 (20 pages)

Numerical modeling of initially turbulent wakes with net momentum

Michael J. Gourlay, S. C. Arendt, D. C. Fritts, and J. Werne

Colorado Research Associates Division/Northwest Research Associates, Inc., 3380 Mitchell Lane, Boulder, Colorado 80302

(Received 22 November 2000; accepted 27 August 2001)

This paper presents results from the first fully three-dimensional direct numerical simulations of initially turbulent wakes with net momentum in unstratified and density stratified fluids. The initial conditions contain a super-position of an initially axisymmetric mean streamwise velocity profile plus a spectrally specified fluctuation velocity field with initially incoherent phases to model initial turbulence. To provide evidence in favor of their validity, we compare results from these simulations with previous measurements behind towed bodies in wind tunnels and towing tanks, and also compare with theories of turbulent wakes. Comparisons with laboratory flow experiments provide agreement, both with statistical quantities and vortex structures and evolution. We subsequently investigate open questions by analysis of the fully three-dimensional flow. Coherent vortices in stratified wakes have their origins in the vortex geometry of the mean wake flow, and do not require stratification or coherent seeding in the initial velocity fluctuations. We conclude that the simulations provide a trustworthy and valuable complement to wake research, and that the vortex structures result from a combination of the necessity that vortices form loops and diffusion of vorticity to smooth the loops into rings. © 2001 American Institute of Physics.

© 2001 American Institute of Physics

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1070-6631 (print)  
1089-7666 (online)

For access to fully linked references, you need to log in.
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    J. M. Chomaz, P. Bonneton, A. Butet, and E. J. Hopfinger, "Vertical diffusion of the far wake of a sphere moving in a stratified fluid," Phys. Fluids A 5, 2799 (1993)PFADEB000005000011002799000001.

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