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Turbulent flows subject to temporal acceleration is considered in this study. Direct numerical simulations of accelerated turbulent wall-bounded flow were performed to study the response of the turbulent structures to temporal acceleration. The simulations were started with the fully-developed turbulent channel flow at an initial Re number, and then a constant temporal acceleration was applied. During the acceleration, the Reynolds number of the channel flow, based on the half-height and the bulk-mean velocity, increased linearly from Re = 3500 to 15000. The conditionally-averaged flow fields associated with changes in turbulent structures were analysed. It is found that the temporal acceleration initially weakened the flow structures before new turbulence was generated later in the near-wall region.
Author(s):
Yongmann Chung
University of Warwick
United Kingdom