%0 Book Section
%T Coherent structures in marginally turbulent square duct flow
publisher Springer
%D 2008
%U 978-1-4020-6471-5
%@ https://hdl.handle.net/20.500.14352/53265
%X Direct numerical simulation of fully developed turbulent flow in a straight square duct was performed in order to determine the minimal requirements for self-sustaining turbulence. It was found that turbulence can be maintained for values of the bulk Reynolds number above approximately 1100, corresponding to a friction-velocity-based Reynolds number of 80. The minimum value for the streamwise period of the computational domain measures around 190 wall units, roughly independently of the Reynolds number. Furthermore, we present a characterization of the marginal state, where coherent structures are found to have significant relevance to the appearance of secondary flow of Prandtl’s second kind.
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