The length and width of the long and wide structures appearing in turbulent Couette flows are studied by means of a new dataset of direct numerical simulation covering a stepped… Click to show full abstract
The length and width of the long and wide structures appearing in turbulent Couette flows are studied by means of a new dataset of direct numerical simulation covering a stepped transition from pure Couette flow to pure Poiseuille one, at Reτ ≈ 130, based on the stationary wall. The existence of these structures is linked to the averaged Reynolds stress, uv¯: as soon as in any part of the channel uv¯ changes its sign, the structures disappear. The length and width of the rolls are found to be, approximately, 50h and 2.5h, respectively. For this Reynolds number, simulations with a domain shorter than 100h cannot properly describe the behaviour of the longest structures of the flow.
Journal Title: Physics of Fluids
Year Published: 2018
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